Image coding device and method, and image decoding device and method

ABSTRACT

The present disclosure relates to an image coding device and method, and an image decoding device and method for enabling the code amount of a chrominance signal in an image to be controlled. A chrominance signal quantization unit determines a luminance signal quantization parameter and a chrominance signal quantization parameter in units of CU by use of a luminance signal quantization parameter, a chrominance signal quantization parameter, and ChromaQPOffset from a rate control unit, and supplies the determined luminance signal quantization parameter and chrominance signal quantization parameter to a quantization unit. The chrominance signal quantization unit calculates a predictive quantization parameter predQP based on the quantization parameters of adjacent CUs. The chrominance signal quantization unit calculates deltaQP and ΔQP C  based on the determined luminance signal quantization parameter and chrominance signal quantization parameter and the calculated predictive quantization parameter predQP. The chrominance signal quantization unit supplies the calculated deltaQP, ΔQP C , and ChromaQPOffset to a lossless coding unit. The present disclosure can be applied to an image processing device, for example.

TECHNICAL FIELD

The present disclosure relates to an image coding device and method, andan image decoding device and method, and particularly to an image codingdevice and method for enabling the code amount of a chrominance signalin an image to be controlled, and an image decoding device and method.

BACKGROUND ART

In recent years, there have been widely used devices for compressing andcoding an image in a coding system for handling image information asdigital information and compressing the same by orthogonal transformsuch as discrete cosine transform and motion compensation by use ofredundancy specific to the image information in order to efficientlytransmit and accumulate information. The coding system may be movingpicture experts group (MPEG), H. 264, MPEG-4 Part 10 (Advanced VideoCoding, denoted as AVC below), and the like, for example.

At present, in order to further enhance the coding efficiency by H.264/AVC, a coding system called high efficiency video coding (HEVC) isbeing standardized by joint collaboration team-video coding (JCTVC)which is a common standard-setting organization with ITU-T and ISO/IEC(Non-Patent Document 1).

BT. 709 color gamut is employed for HD (1920×1080 pixels), but the useof BT. 2020 color gamut for UHD (4000×2000 pixels, 8000×4000 pixels) isbeing discussed. Further, 10-bit or 12-bit bit depth, not 8-bit, isbeing discussed.

CITATION LIST Non-Patent Document

-   Non-Patent Document 1: Benjamin Bross, Woo-Jin Han, Gary J.    Sullivan, Jens-Rainer Ohm, Gary J. Sullivan, Ye-Kui Wang, Thomas    Wiegand, “High Efficiency Video Coding (HEVC) text specification    draft 10 (for FDIS & Consent)”, JCTVC-L1003_v4, Joint Collaborative    Team on Video Coding (JCT-VC) of ITU-T SG 16 WP 3 and ISO/IEC JTC    1/SC 29/WG 11 12th Meeting: Geneva, CH, 14-23 Jan. 2013

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, when image information with wide color gamut is compressed asdescribed above, a larger amount of information is required to code achrominance signal, and the code amount is difficult to sufficientlycontrol with an accuracy of quantization parameter defined in HEVC.

The present disclosure is made in terms of the situation, and isdirected for controlling the code amount of a chrominance signal in animage.

Solutions to Problems

An image coding device of one aspect of the present disclosure includes:a chrominance signal quantization determination unit for determining achrominance signal quantization parameter with a higher quantizationaccuracy than a luminance signal quantization parameter in an image; aquantization unit for quantizing the image by use of the luminancesignal quantization parameter and the chrominance signal quantizationparameter determined by the chrominance signal quantizationdetermination unit; and a coding unit for coding the image quantized bythe quantization unit thereby to generate a coding stream.

The chrominance signal quantization determination unit can determine thechrominance signal quantization parameter such that when the chrominancesignal quantization parameter increases by 12, it is quantized twice ascoarsely as the luminance signal quantization parameter.

A transmission unit for transmitting the coding stream generated by thecoding unit, a parameter deltaQP for the luminance signal, and aparameter ΔQP_(C) for the chrominance signal in a coding unit withpredefined magnitude can further be included.

ΔQP_(C) is calculated in coding unit.

The value of ΔQP_(C) is 0 or 1.

A color space is YCbCr, and the transmission unit can transmit theindependent values of ΔQP_(C) for the Cb signal and the Cr signal.

Assuming a quantization parameter QP_(Y) for the luminance signal, aquantization parameter QP_(C) for the chrominance signal, a quantizationparameter offset offset for the chrominance signal, and a definedrelational equation YtoC between the luminance signal quantizationparameter and the chrominance signal quantization parameter, QP_(C) iscalculated as:

QP _(C)=2*YtoC(QP _(Y)+offset)+ΔQP _(C)  [Mathematical Formula 1]

Assuming a quantization parameter QP_(Y) for the luminance signal, aquantization parameter QP_(C) for the chrominance signal, a quantizationparameter offset offset for the chrominance signal, a defined relationalequation YtoC between the luminance signal quantization parameter andthe chrominance signal quantization parameter, and an integer n of 2 ormore, QP_(C) is calculated as:

QP _(C) =n*YtoC(QP _(Y)+offset)+ΔQP _(C)  [Mathematical Formula 2]

where the value of ΔQPC is 0, 1, 2 . . . , n−1.

A color space is YDzDx.

The chrominance signal quantization determination unit can determine achrominance signal quantization parameter separately from a luminancesignal quantization parameter in an image of an enhancement layer withan input signal with wide color gamut when performing a scalabilitycoding processing based on color gamut scalability.

A chrominance signal quantization parameter offset transmitted togetherwith a coding stream as coded image in the enhancement layer takes anegative value.

When a predetermined flag is 0 in syntax transmitted together with acoding stream as coded image, the chrominance signal quantizationparameter determined by the chrominance signal quantizationdetermination unit is transmitted together with a coded coding stream.

In an image coding method of one aspect of the present disclosure, animage coding device: determines a chrominance signal quantizationparameter with a higher quantization accuracy than a luminance signalquantization parameter in an image, quantizes the image by use of theluminance signal quantization parameter and the determined chrominancesignal quantization parameter, and codes the quantized image thereby togenerate a coding stream.

An image decoding device of one aspect of the present disclosureincludes: a decoding unit for decoding a coding stream thereby togenerate an image a chrominance signal quantization determination unitfor determining a chrominance signal quantization parameter with ahigher quantization accuracy than a luminance signal quantizationparameter in the image generated by the decoding unit; and an inversequantization unit for inversely quantizing the image generated by thedecoding unit by use of the luminance signal quantization parameter andthe chrominance signal quantization parameter determined by thechrominance signal quantization determination unit.

The chrominance signal quantization determination unit can determine thechrominance signal quantization parameter such that when the chrominancesignal quantization parameter increases by 12, it is quantized twice ascoarsely as the luminance signal quantization parameter.

A reception unit for receiving the coding stream, a parameter deltaQPfor the luminance signal, and a parameter ΔQP_(C) for the chrominancesignal in coding unit with predefined magnitude can further be included.

ΔQP_(C) is calculated in coding unit.

The value of ΔQP_(C) is 0 or 1.

A color space is YCbCr, and the reception unit can receive theindependent values of ΔQP_(C) for the Cb signal and the Cr signal.

In an image decoding method of other aspect of the present disclosure,an image decoding device: decodes a coding stream thereby to generate animage, determines a chrominance signal quantization parameter with ahigher quantization accuracy than a luminance signal quantizationparameter in the generated image, and inversely quantizes the generatedimage by use of the luminance signal quantization parameter and thedetermined chrominance signal quantization parameter.

According to one aspect of the present disclosure, a chrominance signalquantization parameter is determined with a higher quantization accuracythan a luminance signal quantization parameter in an image. Then, theimage is quantized by use of the luminance signal quantization parameterand the determined chrominance signal quantization parameter, and thequantized image is coded thereby to generate a coding stream.

According to other aspect of the present disclosure, a coding stream isdecoded thereby to generate an image, and a chrominance signalquantization parameter is determined with a higher quantization accuracythan a luminance signal quantization parameter in the generated image.Then, the generated image is inversely quantized by use of the luminancesignal quantization parameter and the determined chrominance signalquantization parameter.

The image coding device and the image decoding device described abovemay be independent image processing devices, or may be internal blockseach configuring one image coding device or image decoding device.

Effects of the Invention

According to one aspect of the present disclosure, it is possible tocode an image. In particular, it is possible to control the code amountof a chrominance signal in an image.

According to other aspect of the present disclosure, it is possible todecode an image. In particular, it is possible to control the codeamount of a chrominance signal in an image.

The effects described herein are not necessarily limited, and any of theeffects described in the present disclosure may be obtained.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram for explaining an exemplary structure of a codingunit.

FIG. 2 is a diagram for explaining how to code a quantization parameter.

FIG. 3 is a diagram for explaining how to code a quantization parameter.

FIG. 4 is a diagram illustrating a relationship between quantizationparameters for a luminance signal and a chrominance signal.

FIG. 5 is a diagram illustrating a relationship between quantizationparameters for a luminance signal and a chrominance signal.

FIG. 6 is a diagram illustrating color gamut.

FIG. 7 is a diagram illustrating a relationship between a quantizationparameter and a quantization scale.

FIG. 8 is a block diagram illustrating an exemplary structure of a firstexemplary embodiment of a coding device to which the present disclosureis applied.

FIG. 9 is a block diagram illustrating an exemplary structure of thecoding unit of FIG. 1.

FIG. 10 is a block diagram illustrating an exemplary structure of achrominance signal quantization unit.

FIG. 11 is a block diagram illustrating an exemplary structure of achrominance signal inverse quantization unit.

FIG. 12 is a flowchart for explaining a stream generation processing.

FIG. 13 is a flowchart for explaining a coding processing of FIG. 12 indetail.

FIG. 14 is a flowchart for explaining the coding processing of FIG. 12in detail.

FIG. 15 is a flowchart for explaining a flow of a quantization parameterdetermination processing of FIG. 13 by way of example.

FIG. 16 is a flowchart for explaining a flow of a quantization parameterreconstruction processing of FIG. 14 by way of example.

FIG. 17 is a block diagram illustrating an exemplary structure of thefirst exemplary embodiment of a decoding device to which the presentdisclosure is applied.

FIG. 18 is a block diagram illustrating an exemplary structure of adecoding unit of FIG. 17.

FIG. 19 is a flowchart for explaining an image generation processing ofthe decoding device of FIG. 17.

FIG. 20 is a flowchart for explaining a decoding processing of FIG. 19in detail.

FIG. 21 is a block diagram illustrating an exemplary hardware structureof a computer.

FIG. 22 is a diagram illustrating an exemplary multi-view image codingsystem.

FIG. 23 is a diagram illustrating an exemplary structure of a multi-viewimage coding device to which the present disclosure is applied.

FIG. 24 is a diagram illustrating an exemplary structure of a multi-viewimage decoding device to which the present disclosure is applied.

FIG. 25 is a diagram illustrating an exemplary hierarchy image codingsystem.

FIG. 26 is a diagram for explaining spatial scalable coding by way ofexample.

FIG. 27 is a diagram for explaining temporal scalable coding by way ofexample.

FIG. 28 is a diagram for explaining signal-to-noise ratio scalablecoding by way of example.

FIG. 29 is a diagram illustrating an exemplary structure of a hierarchyimage coding device to which the present disclosure is applied.

FIG. 30 is a diagram illustrating an exemplary structure of a hierarchyimage decoding device to which the present disclosure is applied.

FIG. 31 is a diagram illustrating an exemplary schematic structure of aTV set to which the present disclosure is applied.

FIG. 32 is a diagram illustrating an exemplary schematic structure of acell phone to which the present disclosure is applied.

FIG. 33 is a diagram illustrating an exemplary schematic structure of arecording/reproducing device to which the present disclosure is applied.

FIG. 34 is a diagram illustrating an exemplary schematic structure of animaging device to which the present disclosure is applied.

FIG. 35 is a block diagram illustrating exemplary use of scalablecoding.

FIG. 36 is a block diagram illustrating other exemplary use of scalablecoding.

FIG. 37 is a block diagram illustrating still other exemplary use ofscalable coding.

FIG. 38 illustrates an exemplary schematic structure of a video set towhich the present disclosure is applied.

FIG. 39 illustrates an exemplary schematic structure of a videoprocessor to which the present disclosure is applied.

FIG. 40 illustrates other exemplary schematic structure of the videoprocessor to which the present disclosure is applied.

MODE FOR CARRYING OUT THE INVENTION

The modes for carrying out the present disclosure (which will be denotedas exemplary embodiments) will be described below. The description willbe made in the following order.

0. Outline

1. First exemplary embodiment (coding device, decoding device)

2. Second exemplary embodiment (computer)

3. Third exemplary embodiment (multi-view image coding device,multi-view image decoding device)

4. Fourth exemplary embodiment (hierarchy image coding device, hierarchyimage decoding device)

5. Fifth exemplary embodiment (TV set)

6. Sixth exemplary embodiment (cell phone)

7. Seventh exemplary embodiment (recording/reproducing device)

8. Eighth exemplary embodiment (imaging device)

9. Exemplary applications of scalable coding

10. Other exemplary embodiment

0. Outline

(Coding System)

The present technique will be described below assuming that the highefficiency video coding (HEVC) system is applied to imagecoding/decoding.

(Description of Coding Unit)

FIG. 1 is a diagram for explaining Coding UNIT (CU) which is a unit ofcoding in the HEVC system.

The HEVC system is directed for large-size images such as ultra highdefinition (UHD) with 4000 pixels×2000 pixels, and thus it is notoptimum to fix a size of the unit of coding at 16 pixels×16 pixels.Therefore, CU is defined as unit of coding in the HEVC system.

CU plays a similar role to macroblock in the AVC system. Specifically,CU may be divided into PU or divided into TU.

The size of CU is square indicated by as many pixels as a power of 2which is variable per sequence. Specifically, CU is horizontally andvertically divided into two, respectively, arbitrary times to be setsuch that LCU as the maximum size of CU is not smaller than smallestcoding unit (SCU) as the minimum size of CU. That is, the size of anyhierarchy, when LCU is made into hierarchy to be SCU such that the sizeof an upper hierarchy is ¼ times as large as the size of its lowerhierarchy, is the size of CU.

For example, in FIG. 1, the size of LCU is 128 and the size of SCU is 8.Therefore, the hierarchy depth (Depth) of LCU is 0 to 4 and the numberof hierarchy depths is 5. That is, the number of divisions correspondingto CU is any of 0 to 4.

Information for designating the sizes of LCU and SCU is included in SPS.The number of divisions corresponding to CU is designated by split_flagindicating whether to further divide each hierarchy. CU is described inNon-Patent Document 1 in detail.

The size of TU can be designated by use of split_transform_flagsimilarly to split_flag of CU. The maximum numbers of divisions of TUduring inter-prediction and intra-prediction are designated asmax_transform_hierarchy_depth_inter andmax_transform_hierarchy_depth_intra, respectively, by SPS.

The present specification assumes that coding tree unit (CTU) is a unitincluding parameters at the time of a series of processing by codingtree block (CTB) of LCU and its LCU base (level). Further, CUconfiguring CTU is assumed as a unit including parameters at the time ofa series of processing by coding block (CB) and its CU base (level).

(Mode Selection)

In order to achieve a higher coding efficiency, it is important toselect an appropriate prediction mode in the AVC and HEVC codingsystems.

As an example of the selection system, a method mounted on referencesoftware of H. 264/MPEG-4 AVC (published inhttp://iphome.hhi.de/suehring/tml/index.htm), which is called jointmodel (JM), may be listed.

With JM, a mode determination method for High Complexity Mode and LowComplexity Mode described below can be selected. In either mode, a costfunction value for a respective prediction mode Mode is calculated and aprediction mode for minimizing the value is selected as the optimum modefor the block to macroblock.

The cost function in High Complexity Mode is expressed as in thefollowing Equation (1).

Cost(ModeεΩ)=D+λ*R  (1)

Herein, Ω indicates a universal set of candidate modes for coding theblock to macroblock, and D indicates differential energy between adecoded image and an input image when coding is performed in theprediction mode. λ indicates a Lagrange undetermined multiplier given asa function of quantization parameter. R indicates the total code amountwhen coding is performed in the mode, which includes an orthogonaltransform coefficient.

That is, the parameters D and R are calculated in order to performcoding in High Complexity Mode, and thus a temporary encode processingneeds to be performed in all the candidate modes once, which requiresmore computations.

The cost function in Low Complexity Mode is expressed as in thefollowing Equation (2).

Cost(ModeεΩ)=D+QP2Quant(QP)*HeaderBit  (2)

Herein, D indicates differential energy between a predictive image andan input image unlike in High Complexity Mode. QP2Quant (QP) is given asa function of quantization parameter QP, and HeaderBit indicates thecode amount for information belonging to Header, such as motion vectorand mode, which does not include an orthogonal transform coefficient.

That is, the prediction processing needs to be performed in eachcandidate mode in Low Complexity Mode, but the coding processing doesnot need to be performed since a decoded image is not required.Therefore, it can be realized with less computations than in HighComplexity Mode.

(Quantization Parameter Coding System)

A quantization parameter coding system defined in HEVC will be describedbelow.

“Org” illustrated in FIG. 2 indicates a test image of TV conferencecontents of 1280×720 pixels. Quantization control is conducted within apicture by “activity” based on a pixel variance value per macroblockunder rate control such as MPEG-2TestModel5.

Assuming that a quantization parameter can be transmitted only in LCUunit in H. 265/HEVC, a distribution of “activity” of 64×64 unit is “ActBlock=64×64” illustrated in FIG. 2. As can be seen from FIG. 2, a singleBlock includes both a flat region and a region containing texture oredge, and inplane image quality is difficult to control at sufficientgranularity. Similarly to “Act Block=16×16” illustrated in FIG. 2, onlywhen a quantization parameter can be set in Sub-LCU unit, inplane imagequality can be controlled at a similar granularity as in MPEG-2 or AVC.

In HEVC, diff_cu_qp_delta_depth is set in picture parameter set (PPS),and a designation is made as to what depth of coding unit at granularitya quantization parameter can be transmitted for the magnitude of LCU. Acoding unit of the magnitude is called coding unit quantization group(CUQG). The quantization parameter is transmitted in the first transformunit with coded block flag (CBF, which has a non-zero orthogonaltransform coefficient at the value of 1)=1 in CUQG.

A quantization parameter for each coding unit is calculated as in thefollowing Equation (3).

[Mathematical Formula 3]

QP=QP _(PRED) +ΔQP  (3)

ΔQP indicates a differential value relative to a predictive value, whichis transmitted per CUQG. Herein, the quantization parameter predictivevalue QP_(RED) is calculated as in the following Equation (4).

[Mathematical Formula 4]

QP _(PRED)=(qP _(Y) _(_) _(A) +qP _(Y) _(_) _(B)+1)>>1  (4)

Herein, qP_(Y) _(_) _(A) and qP_(Y) _(_) _(B) are the quantizationparameters for CUs positioned at the upper side and the left side to theCU. When the CUs positioned at the upper side and the left side areoutside the LCU, a value of the quantization parameter used for theprevious coding or decoding processing is used as qP_(Y) _(_) _(A) orqP_(Y) _(_) _(B). A diagram for the processing is illustrated in FIG. 3

(Chrominance Signal Quantization Processing)

The chrominance signal quantization processing defined in HEVC will bedescribed below.

A relationship between defaults for a luminance signal and a chrominancesignal is defined as in FIG. 4 or FIG. 5 also in HEVC similarly as inAVC, and a user can adjust it by choma_qp_offset. In the example of FIG.5, a black circle indicates AVC and a triangle indicates HEVC.

In AVC, when only choma_qp_offset is present, it is applied to both ofthe Cb/Cr signals, and when choma_qp_offset and 2nd_choma_qp_offset arepresent, they are applied to Cb and Cr, respectively. To the contrary,in HEVC, cb_qp_offset and cr_qp_offset are applied to Cb and Cr,respectively.

When the maximum value of the luminance signal quantization parametercan take 51 in AVC, while the bits are to be reduced since thechrominance signal quantization parameter is limited to 39 and strictlimitations are imposed by CPB even when an adjustment bychroma_qp_offset is made, desired rate control may be difficult toconduct due to the hindering condition.

In order to solve it, the chrominance signal quantization parameter cantake the maximum value of 51 in HEVC as illustrated in FIG. 4 and FIG.5.

BT. 709 color gamut is employed in HD (1920×1080 pixels) as illustratedin FIG. 6, but the use of BT. 2020 color gamut is being discussed forUHD (4000×2000 pixels, 8000×4000 pixels), and 10-bit or 12-bit bitdepth, not 8-bit, is being discussed.

However, when image information with wide color gamut is compressed asdescribed above, a larger amount of information is required for coding achrominance signal, and the code amount is difficult to sufficientlycontrol with an accuracy of quantization parameter defined in HEVC.

(Operation Principle of Present Technique)

In HEVC, when image information with wide color gamut as illustrated inFIG. 6 is compressed, a larger amount of information is required forcoding a chrominance signal, and the code amount is difficult tosufficiently control with an accuracy of quantization parameter definedin HEVC.

Thus, according to the present technique, as described below, thechrominance signal quantization processing is performed with a higheraccuracy than the luminance signal thereby to enhance ratecontrollability for chrominance signal.

That is, at first, the present technique assumes that the chrominancesignal has a higher accuracy than the luminance signal. Specifically,when the value of the quantization parameter QP exceeds 12, for example,quantization is performed on the chrominance signal at the twice-coarserquantization scale.

Specifically, in AVC and HEVC, the chrominance signal quantizationparameter QP_(C) is calculated as in the following Equation (5) by theluminance signal quantization parameter QP_(Y), the offset, and therelationship YtoC illustrated in FIG. 4 or FIG. 5.

[Mathematical Formula 5]

QP _(C) =YtoC(QP _(Y)+offset)  (5)

To the contrary, according to the present technique, ΔQP_(C) istransmitted in Coding Unit and QP_(C) is calculated as in the followingEquation (6).

[Mathematical Formula 6]

QP _(C)=2*YtoC(QP _(Y)+offset)+ΔQP _(C)  (6)

In HEVC, deltaQP is transmitted for Cording Unit with defined magnitude,the quantization parameter for the CodingUnit is calculated based ondeltaQP and the predictive quantization parameter value predQPcalculated per CodingUnit, and ΔQP_(C) is assumed to be transmitted atthe same time with deltaQP. The value is assumed to be 0 or 1.

Further, the above processing is generalized, and any value of 0, 1, . .. , n−1 may be taken in the following Equation (7), where n is aninteger of 2 or more.

[Mathematical Formula 7]

QP _(C) =n*YtoC(QP _(Y)+offset)+ΔQP _(C)  (7)

The value of n may be transmitted in sequence parameter set (SPS) or thelike in the image compression information to be output. The value may bedifferent between the Cb component and the Cr component.

The value of ΔQP_(C) may be other than 0 and 1. Thereby, according tothe present techniques, the chrominance signal quantization parametervalue can be set independent of the luminance signal per Coring Unit.

The series of processing according to the present technique can beapplied to a color space other than YCbCr, such as YDzDx color space.

Further, flag indicating compatibility with HEVC is transmitted insyntax such as SPS or Picture Parameter Set (PPS) of image compressioninformation to be output, and when the value is 0, the accuracy of thechrominance signal quantization parameter may be extended according tothe present technique.

When the method according to the present technique is realized for colorgamut scalability, it may be applied to an enhancement layer with aninput image signal with wide color gamut. At this time, ChromaQpOffsetin the enhancement layer is set at a negative value on the coding side,thereby enhancing the coding efficiency.

The above series of processing are performed thereby to sufficientlycontrol the code amount. In particular, when a signal with wide colorgamut as illustrated in FIG. 6 is input, rate controllability forchrominance signal can be enhanced.

Exemplary applications of the present technique to specific devices willbe described below.

First Exemplary Embodiment

(Exemplary Structure of Exemplary Embodiment of Coding Device)

FIG. 8 is a block diagram illustrating an exemplary structure of anexemplary embodiment of a coding device to which the present disclosureis applied.

A coding device 10 in FIG. 8 is configured of a setting unit 11, acoding unit 12, and a transmission unit 13, and codes an image in asystem conforming to the HEVC system.

Specifically, the setting unit 11 in the coding device 10 sets videousability information (VUI), supplemental enhancement information (SEI),and the like. The setting unit 11 supplies a parameter set such as theset SPS, PPS, VUI and SEI to the coding unit 12.

The coding unit 12 is input with images in units of frame. The codingunit 12 codes an input image in a system conforming to the HEVC systemwith reference to a parameter set supplied from the setting unit 11. Thecoding unit 12 generates a coding stream based on the coding dataobtained by the coding and the parameter set, and supplies it to thetransmission unit 13.

The transmission unit 13 transmits the coding stream supplied from thecoding unit 12 to a decoding device described below.

(Exemplary Structure of Coding Unit)

FIG. 9 is a block diagram illustrating an exemplary structure of thecoding unit 12 of FIG. 8.

The coding unit 12 of FIG. 9 has an A/D conversion unit 31, a screenrearrangement buffer 32, a computation unit 33, an orthogonal transformunit 34, a quantization unit 35, a lossless coding unit 36, anaccumulation buffer 37, an inverse quantization unit 38, an inverseorthogonal transform unit 39, and an addition unit 40. The coding unit12 further has a deblock filter 41, an adaptive offset filter 42, anadaptive loop filter 43, a frame memory 44, a switch 45, anintra-prediction unit 46, a motion prediction/compensation unit 47, apredictive image selection unit 48, and a rate control unit 49. Thecoding unit 12 further has a chrominance signal quantization unit 50 anda chrominance signal inverse quantization unit 51.

The A/D conversion unit 31 in the coding unit 12 A/D converts an inputimage to be coded in units of frame. The A/D conversion unit 31 outputsand stores the image as converted digital signal into the screenrearrangement buffer 32.

The screen rearrangement buffer 32 rearranges, in the coding order, thestored image in units of frame in the display order depending on the GOPstructure. The screen rearrangement buffer 32 outputs the rearrangedimage to the computation unit 33, the intra-prediction unit 46, and themotion prediction/compensation unit 47.

The computation unit 33 performs coding by subtracting a predictiveimage supplied from the predictive image selection unit 48 from theimage supplied from the screen rearrangement buffer 32. The computationunit 33 outputs the resultant image as residue information(differential) to the orthogonal transform unit 34. When a predictiveimage is not supplied from the predictive image selection unit 48, thecomputation unit 33 outputs the image read from the screen rearrangementbuffer 32 as residue image to the orthogonal transform unit 34.

The orthogonal transform unit 34 performs an orthogonal transformprocessing on the residue information from the computation unit 33 inunits of TU. The orthogonal transform unit 34 supplies an orthogonaltransform processing result after the orthogonal transform processing tothe quantization unit 35.

The size of TU may be 4×4 pixels, 8×8 pixels, 16×16 pixels, and 32×32pixels. The orthogonal transform system may be discrete cosine transform(DCT), for example. A DCT orthogonal transform matrix when TU is 4×4pixels, 8×8 pixels, or 16×16 pixels is obtained by thinning the DCTorthogonal transform matrix with TU of 32×32 pixels to ⅛, ¼ or ½.Therefore, the orthogonal transform unit 34 has only to provide a commoncomputation unit for all the sizes of TU, and does not need to provide acomputation unit per size of TU.

When the optimum prediction mode is an intra-prediction mode and TU has4×4 pixels, Discrete Sine Transform (DST) is employed for the orthogonaltransform system. In this way, when the optimum prediction mode is anintra-prediction mode and TU has 4×4 pixels, or when it is conspicuousthat the residue information is smaller toward the coded surroundingimage, the DST is employed as the orthogonal transform system, and thusthe coding efficiency is enhanced.

The quantization unit 35 quantizes the orthogonal transform processingresult supplied from the orthogonal transform unit 34 by use of aluminance signal quantization parameter and a chrominance signalquantization parameter from the chrominance signal quantization unit 50.The quantization unit 35 supplies the quantization value obtained as aresult of the quantization to the lossless coding unit 36.

The lossless coding unit 36 obtains deltaQP, ΔQPC, and ChromaQPOffset.The lossless coding unit 36 obtains information on the optimumintra-prediction mode (which will be denoted as intra-prediction modeinformation) from the intra-prediction unit 46. Further, the losslesscoding unit 36 obtains information on the optimum inter-prediction mode(which will be denoted as inter-prediction mode information), motionvectors, reference image specification information, and the like fromthe motion prediction/compensation unit 47.

Further, the lossless coding unit 36 obtains offset filter informationon an offset filter from the adaptive offset filter 42, and obtains afilter coefficient from the adaptive loop filter 43.

The lossless coding unit 36 performs lossless coding such as variablelength coding (Context-adaptive variable length coding (CAVLC), forexample) or arithmetic coding (Context-adaptive binary arithmetic coding(CABAC), for example) on the quantization value supplied from thequantization unit 35.

Further, the lossless coding unit 36 losslessly codes as the codinginformation for coding, deltaQP, ΔQPC, ChromaQPOffset, theintra-prediction mode information or the inter-prediction modeinformation, the motion vectors, the reference image specificationinformation, the offset filter information, and the filter coefficients.The lossless coding unit 36 supplies and accumulates thelosslessly-coded coding information and the quantization value as codingdata into the accumulation buffer 37. deltaQP, ΔQPC, and ChromaQPOffsetare losslessly coded and supplied to the chrominance signal inversequantization unit 51.

The losslessly coded coding information may be header information of alosslessly-coded quantization value (such as slice header).

The accumulation buffer 37 temporarily stores the coding data suppliedfrom the lossless coding unit 36. Further, the accumulation buffer 37supplies the stored coding data as a coding stream to the transmissionunit 13 together with the parameter set supplied from the setting unit11 in FIG. 1.

The quantization value output by the quantization unit 35 is input alsointo the inverse quantization unit 38. The inverse quantization unit 38inversely quantizes the quantization value by use of the luminancesignal quantization parameter and the chrominance signal quantizationparameter from the chrominance signal inverse quantization unit 51. Theinverse quantization unit 38 supplies the orthogonal transformprocessing result obtained as a result of the inverse quantization tothe inverse orthogonal transform unit 39.

The inverse orthogonal transform unit 39 performs an inverse orthogonaltransform processing on the orthogonal transform processing resultsupplied from the inverse quantization unit 38 in units of TU. Theinverse orthogonal transform system may be inverse discrete cosinetransform (IDCT) and inverse discrete sine transform (IDST), forexample. The inverse orthogonal transform unit 39 supplies the residueinformation obtained as a result of the inverse orthogonal transformprocessing to the addition unit 40.

The addition unit 40 adds the residue information supplied from theinverse orthogonal transform unit 39 and the predictive image suppliedfrom the predictive image selection unit 48 thereby to perform decoding.The addition unit 40 supplies the decoded image to the deblock filter 41and the frame memory 44.

The deblock filter 41 performs an adaptive deblock filter processing ofremoving a block distortion on the decoded image supplied by theaddition unit 40, and supplies the resultant image to the adaptiveoffset filter 42.

The adaptive offset filter 42 performs an adaptive offset filter (Sampleadaptive offset (SAO)) processing of mainly removing ringing on theimage subjected to the adaptive deblock filter processing by the deblockfilter 41.

Specifically, the adaptive offset filter 42 determines a type of theadaptive offset filter processing per largest coding unit (LCU) as themaximum unit of coding, and finds an offset used for the adaptive offsetfilter processing. The adaptive offset filter 42 uses the found offsetto perform the adaptive offset filter processing of the determined typeon the image subjected to the adaptive deblock filter processing.

The adaptive offset filter 42 supplies the image subjected to theadaptive offset filter processing to the adaptive loop filter 43.Further, the adaptive offset filter 42 supplies the information on thetype of the performed adaptive offset filter processing and the offsetas offset filter information to the lossless coding unit 36.

The adaptive loop filter 43 is configured of a 2D Wiener filter, forexample. The adaptive loop filter 43 performs an adaptive loop filter(ALF) processing on the image subjected to the adaptive offset filterprocessing supplied from the adaptive offset filter 42 per LCU, forexample.

Specifically, the adaptive loop filter 43 calculates a filtercoefficient used for the adaptive loop filter processing per LCU suchthat the residue of the original image output from the screenrearrangement buffer 32 and the image subjected to the adaptive loopfilter processing is minimum. The adaptive loop filter 43 then performsthe adaptive loop filter processing on the image subjected to theadaptive offset filter processing per LCU by use of the calculatedfilter coefficient.

The adaptive loop filter 43 supplies the image subjected to the adaptiveloop filter processing to the frame memory 44. Further, the adaptiveloop filter 43 supplies the filter coefficient used for the adaptiveloop filter processing to the lossless coding unit 36.

Herein, the adaptive loop filter processing is assumed to be performedper LCU, but the processing unit of the adaptive loop filter processingis not limited to LCU. The processing units of the adaptive offsetfilter 42 and the adaptive loop filter 43 are matched, therebyefficiently performing the series of processing.

The frame memory 44 accumulates the image supplied from the adaptiveloop filter 43 and the image supplied from the addition unit 40. Theimages adjacent to prediction unit (PU), among the images which areaccumulated in the frame memory 44 and are not subjected to the filterprocessing, are supplied as surrounding images to the intra-predictionunit 46 via the switch 45. On the other hand, the images accumulated inthe frame memory 44 and subjected to the filter processing are output asreference images to the motion prediction/compensation unit 47 via theswitch 45.

The intra-prediction unit 46 performs an intra-prediction processing inall the candidate intra-prediction modes by use of the surroundingimages read from the frame memory 44 via the switch 45 in units of PU.

Further, the intra-prediction unit 46 calculates the cost functionvalues (described below in detail) for all the candidateintra-prediction modes based on the image read from the screenrearrangement buffer 32 and the predictive image generated as a resultof the intra-prediction processing. The intra-prediction unit 46 thendetermines an intra-prediction mode for which the cost function value isminimum as the optimum intra-prediction mode.

The intra-prediction unit 46 supplies the predictive image generated inthe optimum intra-prediction mode and the corresponding cost functionvalue to the predictive image selection unit 48. When notified of theselection of the predictive image generated in the optimumintra-prediction mode from the predictive image selection unit 48, theintra-prediction unit 46 supplies intra-prediction mode information tothe lossless coding unit 36. The intra-prediction mode is a modeindicating a size of PU, a prediction direction, and the like.

The motion prediction/compensation unit 47 performs a motionprediction/compensation processing in all the candidate inter-predictionmodes in units of PU. Specifically, the motion prediction/compensationunit 47 detects motion vectors in all the candidate inter-predictionmodes in units of PU based on the image supplied from the screenrearrangement buffer 32 and the reference image read from the framememory 44 via the switch 45. The motion prediction/compensation unit 47then performs a compensation processing on the reference image in unitsof PU based on the motion vectors, thereby to generate a predictiveimage.

At this time, the motion prediction/compensation unit 47 calculates thecost function values for all the candidate inter-prediction modes basedon the image supplied from the screen rearrangement buffer 32 and thepredictive image, and determines an inter-prediction mode for which thecost function value is minimum as the optimum inter-prediction mode. Themotion prediction/compensation unit 47 then supplies the cost functionvalue in the optimum inter-prediction mode and the correspondingpredictive image to the predictive image selection unit 48. Further, themotion prediction/compensation unit 47 outputs the inter-prediction modeinformation generated in the optimum inter-prediction mode, thecorresponding motion vectors, the reference image specificationinformation, and the like from the predictive image selection unit 48 tothe lossless coding unit 36. The inter-prediction mode is a modeindicating a size of PU and the like.

The predictive image selection unit 48 determines either the optimumintra-prediction mode or the optimum inter-prediction mode, for whichthe corresponding cost function value is smaller, as the optimumprediction mode based on the cost function values supplied from theintra-prediction unit 46 and the motion prediction/compensation unit 47.The predictive image selection unit 48 then supplies the predictiveimage in the optimum prediction mode to the computation unit 33 and theaddition unit 40. Further, the predictive image selection unit 48notifies the selection of the predictive image in the optimum predictionmode to the intra-prediction unit 46 or the motionprediction/compensation unit 47.

The rate control unit 49 controls a rate of the quantization operationof the quantization unit 35 based on the coding data accumulated in theaccumulation buffer 37 in order to prevent overflow or underflow fromoccurring. Further, the rate control unit 49 supplies the luminancesignal quantization parameter, the chrominance signal quantizationparameter, and ChromaQPOffset to the chrominance signal quantizationunit 50.

The chrominance signal quantization unit 50 determines a luminancesignal quantization parameter and a chrominance signal quantizationparameter in units of CU by use of the luminance signal quantizationparameter, the chrominance signal quantization parameter, andChromaQPOffset from the rate control unit 49. The chrominance signalquantization unit 50 supplies the determined luminance signalquantization parameter and chrominance signal quantization parameter tothe quantization unit 35.

Further, the chrominance signal quantization unit 50 calculates apredictive quantization parameter predQP from the quantizationparameters of the adjacent CUs. The chrominance signal quantization unit50 calculates deltaQP and ΔQP_(C) from the determined luminance signalquantization parameter and chrominance signal quantization parameter andthe calculated predictive quantization parameter predQP. The chrominancesignal quantization unit 50 supplies the calculated deltaQP, ΔQP_(C),and ChromaQPOffset to the lossless coding unit 36.

The chrominance signal inverse quantization unit 51 receives deltaQP,ΔQP_(C), and ChromaQPOffset from the lossless coding unit 36. Thechrominance signal inverse quantization unit 51 calculates thepredictive quantization parameter predQP from the quantizationparameters in the adjacent CUs. The chrominance signal inversequantization unit 51 reconstructs the luminance signal quantizationparameter by deltaQP and predQP thereby to determine the luminancesignal quantization parameter. The chrominance signal inversequantization unit 51 then supplies the determined luminance signalquantization parameter to the inverse quantization unit 38.

The chrominance signal inverse quantization unit 51 reconstructs thechrominance signal quantization parameter by the reconstructed luminancesignal quantization parameter, ΔQP_(C), and ChromaQPOffset thereby todetermine the chrominance signal quantization parameter. The chrominancesignal inverse quantization unit 51 supplies the determined chrominancesignal quantization parameter to the inverse quantization unit 38.

(Exemplary Structure of Chrominance Signal Quantization Unit)

FIG. 10 is a block diagram illustrating an exemplary structure of thechrominance signal quantization unit 50 of FIG. 9.

The chrominance signal quantization unit 50 in FIG. 10 is configured toinclude a luminance signal quantization parameter buffer 81, achrominance signal quantization parameter buffer 82, a ChromaQPOffsetbuffer 83, a deltaQP calculation unit 84, an adjacent QP buffer 85, aΔQPC calculation unit 86, and a predQP calculation unit 87.

The luminance signal quantization parameter, the chrominance signalquantization parameter and ChromaQPOffset are supplied from the ratecontrol unit 49 to the luminance signal quantization parameter buffer81, the chrominance signal quantization parameter buffer 82, and theChromaQPOffset buffer 83, respectively.

The luminance signal quantization parameter buffer 81 accumulates theluminance signal quantization parameter from the rate control unit 49,and determines it as a luminance signal quantization parameter for theCU. The luminance signal quantization parameter buffer 81 supplies thedetermined luminance signal quantization parameter to the quantizationunit 35, the deltaQP calculation unit 84, the adjacent QP buffer 85, andthe ΔQPC calculation unit 86.

The chrominance signal quantization parameter buffer 82 accumulates thechrominance signal quantization parameter from the rate control unit 49,and determines it as a chrominance signal quantization parameter for theCU. The chrominance signal quantization parameter buffer 82 supplies thedetermined chrominance signal quantization parameter to the quantizationunit 35 and the ΔQPC calculation unit 86.

The ChromaQPOffset buffer 83 accumulates ChromaQPOffset from the ratecontrol unit 49, and supplies it to the ΔQPC calculation unit 86 and thelossless coding unit 36.

The deltaQP calculation unit 84 calculates deltaQP by use of theluminance signal quantization parameter for the CU from the luminancesignal quantization parameter buffer 81 and predQP from the predQPcalculation unit 87. The deltaQP calculation unit 84 supplies thecalculated deltaQP to the lossless coding unit 36.

The adjacent QP buffer 85 accumulates the luminance signal quantizationparameter from the luminance signal quantization parameter buffer 81,and supplies it as a luminance quantization parameter for adjacent CU(which will be denoted as adjacent quantization parameter) to the predQPcalculation unit 87.

The ΔQPC calculation unit 86 calculates ΔQPC by use of the luminancesignal quantization parameter from the luminance signal quantizationparameter buffer 81, the chrominance signal quantization parameter fromthe chrominance signal quantization parameter buffer 82, andChromaQPOffset from the ChromaQPOffset buffer 83. The ΔQPC calculationunit 86 supplies the calculated ΔQPC to the lossless coding unit 36.

The predQP calculation unit 87 calculates predQP in a method defined inHEVC or the like by use of the adjacent quantization parameter from theadjacent QP buffer 85. The predQP calculation unit 87 supplies thecalculated predQP to the deltaQP calculation unit 84.

(Exemplary Structure of Chrominance Signal Inverse Quantization Unit)

FIG. 11 is a block diagram illustrating an exemplary structure of thechrominance signal inverse quantization unit 51 of FIG. 9.

The chrominance signal inverse quantization unit 51 in FIG. 11 isconfigured to include a luminance signal quantization parameterreconstruction unit 91, a chrominance signal quantization parameterreconstruction unit 92, a ChromaQPOffset reception unit 93, a deltaQPreception unit 94, an adjacent QP buffer 95, a ΔQPC reception unit 96,and a predQP calculation unit 97.

deltaQP, ΔQPC, and ChromaQPOffset are supplied from the lossless codingunit 36 to the deltaQP reception unit 94, the ΔQPC reception unit 96,and the ChromaQPOffset reception unit 93, respectively.

The luminance signal quantization parameter reconstruction unit 91reconstructs the luminance signal quantization parameter by use ofdeltaQP from the deltaQP reception unit 94 and predQP from the predQPcalculation unit 97. The luminance signal quantization parameterreconstruction unit 91 supplies the reconstructed luminance signalquantization parameter to the inverse quantization unit 38, thechrominance signal quantization parameter reconstruction unit 92, andthe adjacent QP buffer 95.

The chrominance signal quantization parameter reconstruction unit 92reconstructs the chrominance signal quantization parameter by use ofΔQPC from the ΔQPC reception unit 96, ChromaQPOffset from theChromaQPOffset reception unit 93, and the luminance signal quantizationparameter from the luminance signal quantization parameterreconstruction unit 91. The chrominance signal quantization parameterreconstruction unit 92 supplies the reconstructed chrominance signalquantization parameter to the inverse quantization unit 38.

The ChromaQPOffset reception unit 93 receives ChromaQPOffset from thelossless coding unit 36, and supplies it to the chrominance signalquantization parameter reconstruction unit 92.

The deltaQP reception unit 94 receives deltaQP from the lossless codingunit 36, and supplies it to the luminance signal quantization parameterreconstruction unit 91.

The adjacent QP buffer 95 accumulates the luminance signal quantizationparameter from the luminance signal quantization parameterreconstruction unit 91, and supplies it as adjacent quantizationparameter to the predQP calculation unit 97.

The ΔQPC reception unit 96 receives ΔQPC from the lossless coding unit36, and supplies it to the chrominance signal quantization parameterreconstruction unit 92.

The predQP calculation unit 97 calculates predQP in a method defined inHEVC or the like by use of the adjacent quantization parameter from theadjacent QP buffer 95. The predQP calculation unit 97 supplies thecalculated predQP to the luminance signal quantization parameterreconstruction unit 91.

(Description of Series of Processing in Coding Device)

FIG. 12 is a flowchart for explaining a stream generation processing inthe coding device 10 of FIG. 8.

In step S11 in FIG. 12, the setting unit 11 in the coding device 10 setsa parameter set. The setting unit 11 supplies the set parameter set tothe coding unit 12.

In step S12, the coding unit 12 performs the coding processing of codingan externally-input image in units of frame in a system conforming tothe HEVC system. The coding processing will be described below in detailwith reference to FIG. 13 and FIG. 14.

In step S13, the accumulation buffer 37 (FIG. 9) in the coding unit 12generates a coding stream based on the parameter set supplied from thesetting unit 11 and the accumulated coding data, and supplies it to thetransmission unit 13.

In step S14, the transmission unit 13 transmits the coding streamsupplied from the setting unit 11 to a decoding device 110 describedbelow, and terminates the processing.

FIG. 13 and FIG. 14 are the flowcharts for explaining the codingprocessing in step S12 in FIG. 12 in detail.

In step S31 in FIG. 13, the A/D conversion unit 31 (FIG. 9) in thecoding unit 12 A/D converts the input image to be coded in units offrame. The A/D conversion unit 31 outputs and stores the converted imageas digital signal into the screen rearrangement buffer 32.

In step S32, the screen rearrangement buffer 32 rearranges, in thecoding order, the stored images of the frames in the display orderdepending on the GOP structure. The screen rearrangement buffer 32supplies the rearranged images in units of frame to the computation unit33, the intra-prediction unit 46, and the motion prediction/compensationunit 47.

In step S33, the intra-prediction unit 46 performs the intra-predictionprocessing in all the candidate intra-prediction modes in units of PU.Further, the intra-prediction unit 46 calculates the cost functionvalues for all the candidate intra-prediction modes based on the imageread from the screen rearrangement buffer 32 and the predictive imagegenerated as a result of the intra-prediction processing. Theintra-prediction unit 46 then determines an intra-prediction mode forwhich the cost function value is minimum as the optimum intra-predictionmode. The intra-prediction unit 46 supplies the predictive imagegenerated in the optimum intra-prediction mode and the correspondingcost function value to the predictive image selection unit 48.

Further, the motion prediction/compensation unit 47 performs the motionprediction/compensation processing in all the candidate inter-predictionmodes in units of PU. Further, the motion prediction/compensation unit47 calculates the cost function values for all the candidateinter-prediction modes based on the image supplied from the screenrearrangement buffer 32 and the predictive image, and determines aninter-prediction mode for which the cost function value is minimum asthe optimum inter-prediction mode. The motion prediction/compensationunit 47 then supplies the cost function value in the optimuminter-prediction mode and the corresponding predictive image to thepredictive image selection unit 48.

In step S34, the predictive image selection unit 48 determines eitherthe optimum intra-prediction mode or the optimum inter-prediction modefor which the cost function value is minimum as the optimum predictionmode based on the cost function values supplied from theintra-prediction unit 46 and the motion prediction/compensation unit 47in the processing in step S33. The predictive image selection unit 48then supplies the predictive image in the optimum prediction mode to thecomputation unit 33 and the addition unit 40.

In step S35, the predictive image selection unit 48 determines whetherthe optimum prediction mode is the optimum inter-prediction mode. Whenit is determined in step S35 that the optimum prediction mode is theoptimum inter-prediction mode, the predictive image selection unit 48notifies the selection of the predictive image generated in the optimuminter-prediction mode to the motion prediction/compensation unit 47.

Then, in step S36, the motion prediction/compensation unit 47 suppliesthe inter-prediction mode information, the motion vectors, and thereference image specification information to the lossless coding unit36, and the processing proceeds to step S38.

On the other hand, when it is determined in step S35 that the optimumprediction mode is not the optimum inter-prediction mode, or when theoptimum prediction mode is the optimum intra-prediction mode, thepredictive image selection unit 48 notifies the selection of thepredictive image generated in the optimum intra-prediction mode to theintra-prediction unit 46. Then, in step S37, the intra-prediction unit46 supplies the intra-prediction mode information to the lossless codingunit 36, and the processing proceeds to step S38.

In step S38, the computation unit 33 performs coding by subtracting thepredictive image supplied from the predictive image selection unit 48from the image supplied from the screen rearrangement buffer 32. Thecomputation unit 33 outputs the resultant image as residue informationto the orthogonal transform unit 34.

In step S39, the orthogonal transform unit 34 performs the orthogonaltransform processing on the residue information in units of TU. Theorthogonal transform unit 34 supplies the orthogonal transformprocessing result after the orthogonal transform processing to thequantization unit 35.

In step S40, the chrominance signal quantization unit 50 performs aquantization parameter determination processing. The quantizationparameter determination processing will be described below in detailwith reference to FIG. 15.

In the processing in step S40, the determined luminance signal andchrominance signal, and their respective quantization parameters aresupplied to the quantization unit 35. Further, the calculated deltaQP,ΔQPC, and ChromaQPOffset are supplied to the lossless coding unit 36.

In step S41, the quantization unit 35 quantizes the orthogonal transformprocessing result supplied from the orthogonal transform unit 34 by useof the luminance signal quantization parameter and the chrominancesignal quantization parameter from the chrominance signal quantizationunit 50. The quantization unit 35 supplies the quantization valueobtained as a result of the quantization to the lossless coding unit 36and the inverse quantization unit 38.

The lossless coding unit 36 supplies deltaQP, ΔQPC, and ChromaQPOffsetfrom the quantization unit 35 to the chrominance signal inversequantization unit 51.

In step S42 in FIG. 14, the chrominance signal inverse quantization unit51 performs a quantization parameter reconstruction processing. Thequantization parameter reconstruction processing will be described belowin detail with reference to FIG. 16.

In the processing in step S42, there constructed luminance signal andchrominance signal, and their respective quantization parameters aresupplied to the inverse quantization unit 38.

In step S43, the inverse quantization unit 38 inversely quantizes thequantization value from the quantization unit 35 by use of the luminancesignal quantization parameter and the chrominance signal quantizationparameter from the chrominance signal inverse quantization unit 51. Theinverse quantization unit 38 supplies the orthogonal transformprocessing result obtained as a result of the inverse quantization tothe inverse orthogonal transform unit 39.

In step S44, the inverse orthogonal transform unit 39 performs theinverse orthogonal transform processing on the orthogonal transformprocessing result supplied from the inverse quantization unit 38 inunits of TU. The inverse orthogonal transform unit 39 supplies theresidue information obtained as a result of the inverse orthogonaltransform processing to the addition unit 40.

In step S45, the addition unit 40 adds the residue information suppliedfrom the inverse orthogonal transform unit 39 and the predictive imagesupplied from the predictive image selection unit 48 thereby to performdecoding. The addition unit 40 supplies the decoded image to the deblockfilter 41 and the frame memory 44.

In step S46, the deblock filter 41 performs a deblocking filterprocessing on the decoded image supplied from the addition unit 40. Thedeblock filter 41 supplies the resultant image to the adaptive offsetfilter 42.

In step S47, the adaptive offset filter 42 performs the adaptive offsetfilter processing on the image supplied from the deblock filter 41 perLCU. The adaptive offset filter 42 supplies the resultant image to theadaptive loop filter 43. Further, the adaptive offset filter 42 suppliesthe offset filter information to the lossless coding unit 36 per LCU.

In step S48, the adaptive loop filter 43 performs the adaptive loopfilter processing on the image supplied from the adaptive offset filter42 per LCU. The adaptive loop filter 43 supplies the resultant image tothe frame memory 44. Further, the adaptive loop filter 43 supplies thefilter coefficient used in the adaptive loop filter processing to thelossless coding unit 36.

In step S49, the frame memory 44 accumulates the image supplied from theadaptive loop filter 43 and the image supplied from the addition unit40. The images adjacent to PU, among the images which are accumulated inthe frame memory 44 and are not subjected to the filter processing, aresupplied as surrounding images to the intra-prediction unit 46 via theswitch 45. On the other hand, the images accumulated in the frame memory44 and subjected to the filter processing are output as reference imagesto the motion prediction/compensation unit 47 via the switch 45.

In step S50, the lossless coding unit 36 losslessly codes theintra-prediction mode information or the inter-prediction modeinformation, the motion vectors, the reference image specificationinformation, deltaQP, ΔQPC, ChromaQPOffset, the offset filterinformation, and the filter coefficient as the coding information.

In step S51, the lossless coding unit 36 losslessly codes thequantization value supplied from the quantization unit 35. The losslesscoding unit 36 then generates coding data based on the codinginformation losslessly coded in the processing in step S50 and thelosslessly-coded quantization value, and supplies it to the accumulationbuffer 37.

In step S52, the accumulation buffer 37 temporarily accumulates thecoding data supplied from the lossless coding unit 36.

In step S53, the rate control unit 49 controls a rate of thequantization operation of the quantization unit 35 based on the codingdata accumulated in the accumulation buffer 37 in order to preventoverflow or underflow from occurring. Further, the rate control unit 49supplies the luminance signal quantization parameter, the chrominancesignal quantization parameter, and ChromaQPOffset to the chrominancesignal quantization unit 50. The processing then returns to step S12 inFIG. 12 and proceeds to step S13.

The intra-prediction processing and the motion prediction/compensationprocessing are assumed to be always performed in the coding processingin FIG. 13 and FIG. 14 for simplified description, but actually eitherone of them may be performed depending on picture type or the like.

FIG. 15 is a flowchart for explaining the quantization parameterdetermination processing in step S40 in FIG. 13.

The luminance signal quantization parameter, the chrominance signalquantization parameter, and ChromaQPOffset are supplied and accumulatedfrom the rate control unit 49 into the luminance signal quantizationparameter buffer 81, the chrominance signal quantization parameterbuffer 82, and the ChromaQPOffset buffer 83, respectively.

In step S71, the luminance signal quantization parameter buffer 81determines the luminance signal quantization parameter from the ratecontrol unit 49 as luminance signal quantization parameter for the CU,for example. The luminance signal quantization parameter buffer 81supplies the determined luminance signal quantization parameter to thequantization unit 35, the deltaQP calculation unit 84, the adjacent QPbuffer 85, and the ΔQPC calculation unit 86.

In step S72, the chrominance signal quantization parameter buffer 82determines the chrominance signal quantization parameter from the ratecontrol unit 49 as chrominance signal quantization parameter for the CU,for example. The chrominance signal quantization parameter buffer 82supplies the determined chrominance signal quantization parameter to thequantization unit 35 and the ΔQPC calculation unit 86.

The adjacent QP buffer 85 accumulates the luminance signal quantizationparameter from the luminance signal quantization parameter buffer 81,and supplies it as luminance quantization parameter for adjacent CU(which will be denoted as adjacent quantization parameter below) to thepredQP calculation unit 87.

In step S73, the predQP calculation unit 87 calculates predQP in amethod defined in HEVC or the like by use of the adjacent quantizationparameter from the adjacent QP buffer 85. The predQP calculation unit 87supplies the calculated predQP to the deltaQP calculation unit 84.

In step S74, the deltaQP calculation unit 84 calculates deltaQP by useof the luminance signal quantization parameter for the CU from theluminance signal quantization parameter buffer 81 and predQP from thepredQP calculation unit 87. The deltaQP calculation unit 84 supplies thecalculated deltaQP to the lossless coding unit 36.

In step S75, the ΔQPC calculation unit 86 calculates ΔQPC by use of theluminance signal quantization parameter from the luminance signalquantization parameter buffer 81, the chrominance signal quantizationparameter from the chrominance signal quantization parameter buffer 82,and ChromaQPOffset from the ChromaQPOffset buffer 83. The ΔQPCcalculation unit 86 supplies the calculated ΔQPC to the lossless codingunit 36.

FIG. 16 is a flowchart for explaining the quantization parameterreconstruction processing in step S42 in FIG. 14.

deltaQP, ΔQPC, and ChromaQPOffset are supplied from the lossless codingunit 36 to the deltaQP reception unit 94, the ΔQPC reception unit 96,and the ChromaQPOffset reception unit 93, respectively. TheChromaQPOffset reception unit 93 receives ChromaQPOffset from thelossless coding unit 36 at a predetermined timing, and supplies it tothe chrominance signal quantization parameter reconstruction unit 92.

In step S91, the deltaQP reception unit 94 receives deltaQP from thelossless coding unit 36. The deltaQP reception unit 94 supplies thereceived deltaQP to the luminance signal quantization parameterreconstruction unit 91.

In step S92, the predQP calculation unit 97 calculates predQP in amethod defined in HEVC or the like by use of the adjacent quantizationparameter from the adjacent QP buffer 95. The predQP calculation unit 97supplies the calculated predQP to the luminance signal quantizationparameter reconstruction unit 91.

In step S93, the luminance signal quantization parameter reconstructionunit 91 reconstructs the luminance signal quantization parameter by useof deltaQP from the deltaQP reception unit 94 and predQP from the predQPcalculation unit 97. The luminance signal quantization parameterreconstruction unit 91 supplies the reconstructed luminance signalquantization parameter to the inverse quantization unit 38, thechrominance signal quantization parameter reconstruction unit 92, andthe adjacent QP buffer 95.

In step S94, the ΔQPC reception unit 96 receives ΔQPC from the losslesscoding unit 36. The ΔQPC reception unit 96 supplies the received ΔQPC tothe chrominance signal quantization parameter reconstruction unit 92.

In step S95, the chrominance signal quantization parameterreconstruction unit 92 reconstructs the chrominance signal quantizationparameter by use of ΔQPC from the ΔQPC reception unit 96, ChromaQPOffsetfrom the ChromaQPOffset reception unit 93, and the luminance signalquantization parameter from the luminance signal quantization parameterreconstruction unit 91. The chrominance signal quantization parameterreconstruction unit 92 supplies the reconstructed chrominance signalquantization parameter to the inverse quantization unit 38.

As described above, ΔQPC is calculated and is sent to the decoding sideat the same time with deltaQP, and thus the code amount of thechrominance signal in an image can be controlled. In particular, when asignal with wide color gamut is input, rate controllability forchrominance signal can be enhanced.

(Exemplary Structure of Exemplary Embodiment of Decoding Device)

FIG. 17 is a block diagram illustrating an exemplary structure of anexemplary embodiment of the decoding device, to which the presentdisclosure is applied, for decoding a coding stream transmitted from thecoding device 10 in FIG. 8.

The decoding device 110 in FIG. 17 is configured of a reception unit111, an extraction unit 112, and a decoding unit 113.

The reception unit 111 in the decoding device 110 receives a codingstream transmitted from the coding device 10 in FIG. 8, and supplies itto the extraction unit 112.

The extraction unit 112 extracts the parameter set and the coding datafrom the coding stream supplied from the reception unit 111, andsupplies them to the decoding unit 113.

The decoding unit 113 decodes the coding data supplied from theextraction unit 112 in a system conforming to the HEVC system. At thistime, the decoding unit 113 refers to the parameter set supplied fromthe extraction unit 112 as needed. The decoding unit 113 outputs theimage obtained as a result of the decoding.

(Exemplary Structure of Decoding Unit)

FIG. 18 is a block diagram illustrating an exemplary structure of thedecoding unit 113 of FIG. 17.

The decoding unit 113 in FIG. 18 has an accumulation buffer 131, alossless decoding unit 132, an inverse quantization unit 133, an inverseorthogonal transform unit 134, an addition unit 135, a deblock filter136, an adaptive offset filter 137, an adaptive loop filter 138, and ascreen rearrangement buffer 139. The decoding unit 113 further has a D/Aconversion unit 140, a frame memory 141, a switch 142, anintra-prediction unit 143, a motion compensation unit 144, a switch 145,and a chrominance signal inverse quantization unit 146.

The accumulation buffer 131 in the decoding unit 113 receives andaccumulates the coding data from the extraction unit 112 in FIG. 17. Theaccumulation buffer 131 supplies the accumulated coding data to thelossless decoding unit 132.

The lossless decoding unit 132 performs lossless decoding such asvariable length decoding or arithmetic decoding on the coding data fromthe accumulation buffer 131 thereby to obtain the quantization value andthe coding information. The lossless decoding unit 132 supplies thequantization value to the inverse quantization unit 133. Further, thelossless decoding unit 132 supplies the intra-prediction modeinformation as the coding information to the intra-prediction unit 143.The lossless decoding unit 132 supplies the motion vectors, theinter-prediction mode information, the reference image specificationinformation, and the like to the motion compensation unit 144.

Further, the lossless decoding unit 132 supplies the intra-predictionmode information or the inter-prediction mode information as the codinginformation to the switch 145. The lossless decoding unit 132 suppliesthe offset filter information as the coding information to the adaptiveoffset filter 137. The lossless decoding unit 132 supplies the filtercoefficient as the coding information to the adaptive loop filter 138.

Further, the lossless decoding unit 132 supplies deltaQP, ΔQPC, andChromaQPOffset as the coding information to the chrominance signalinverse quantization unit 146.

The inverse quantization unit 133, the inverse orthogonal transform unit134, the addition unit 135, the deblock filter 136, the adaptive offsetfilter 137, the adaptive loop filter 138, the frame memory 141, theswitch 142, the intra-prediction unit 143, the motion compensation unit144, and the chrominance signal inverse quantization unit 146 performthe same series of processing as the inverse quantization unit 38, theinverse orthogonal transform unit 39, the addition unit 40, the deblockfilter 41, the adaptive offset filter 42, the adaptive loop filter 43,the frame memory 44, the switch 45, the intra-prediction unit 46, themotion prediction/compensation unit 47, and the chrominance signalinverse quantization unit 51 in FIG. 9, respectively, thereby to decodean image.

Specifically, the inverse quantization unit 133 is configured in thesame way as the inverse quantization unit 38 in FIG. 9. The inversequantization unit 133 inversely quantizes the quantization value fromthe lossless decoding unit 132 in units of TU. The inverse quantizationunit 133 supplies the resultant orthogonal transform processing resultto the inverse orthogonal transform unit 134.

The inverse orthogonal transform unit 134 is configured in the same wayas the inverse orthogonal transform unit 39 in FIG. 9. The inverseorthogonal transform unit 134 performs the inverse orthogonal transformprocessing on the orthogonal transform processing result supplied fromthe inverse quantization unit 133 by use of the luminance signalquantization parameter and the chrominance signal quantization parametersupplied from the chrominance signal inverse quantization unit 146. Theinverse orthogonal transform unit 134 supplies the residue informationobtained as a result of the inverse orthogonal transform processing tothe addition unit 135.

The addition unit 135 adds the residue information supplied from theinverse orthogonal transform unit 134 and the predictive image suppliedfrom the switch 145 thereby to perform decoding. The addition unit 135supplies the decoded image to the deblock filter 136 and the framememory 141.

The deblock filter 136 performs the adaptive deblock filter processingon the image supplied from the addition unit 135, and supplies theresultant image to the adaptive offset filter 137.

The adaptive offset filter 137 performs the adaptive offset filterprocessing of the type indicated by the offset filter information perLCU on the image subjected to the adaptive deblock filter processing byuse of the offset indicated by the offset filter information from thelossless decoding unit 132. The adaptive offset filter 137 supplies theimage subjected to the adaptive offset filter processing to the adaptiveloop filter 138.

The adaptive loop filter 138 performs the adaptive loop filterprocessing on the image supplied from the adaptive offset filter 137 perLCU by use of the filter coefficient supplied from the lossless decodingunit 132. The adaptive loop filter 138 supplies the resultant image tothe frame memory 141 and the screen rearrangement buffer 139.

The screen rearrangement buffer 139 stores the image supplied from theadaptive loop filter 138 in units of frame. The screen rearrangementbuffer 139 rearranges, in the original display order, the stored imagein units of frame in the coding order, and supplies it to the D/Aconversion unit 140.

The D/A conversion unit 140 D/A converts and outputs the image in unitsof frame supplied from the screen rearrangement buffer 139.

The frame memory 141 accumulates the image supplied from the adaptiveloop filter 138 and the image supplied from the addition unit 135. Theimages adjacent to PU, among the images which are accumulated in theframe memory 141 and are not subjected to the filter processing, aresupplied as surrounding images to the intra-prediction unit 143 via theswitch 142. On the other hand, the images accumulated in the framememory 141 and subjected to the filter processing are supplied asreference images to the motion compensation unit 144 via the switch 142.

The intra-prediction unit 143 performs the intra-prediction processingin the optimum intra-prediction mode indicated by the intra-predictionmode information supplied from the lossless decoding unit 132 by use ofthe surrounding images read from the frame memory 141 via the switch142. The intra-prediction unit 143 supplies the resultant predictiveimage to the switch 145.

The motion compensation unit 144 reads the reference image specified bythe reference image specification information supplied from the losslessdecoding unit 132 from the frame memory 141 via the switch 142. Themotion compensation unit 144 performs the motion compensation processingin the optimum inter-prediction mode indicated by the inter-predictionmode information supplied from the lossless decoding unit 132 by use ofthe motion vectors and the reference image supplied from the losslessdecoding unit 132. The motion compensation unit 144 supplies theresultant predictive image to the switch 145.

When supplied with the intra-prediction mode information from thelossless decoding unit 132, the switch 145 supplies the predictive imagesupplied from the intra-prediction unit 143 to the addition unit 135. Onthe other hand, when supplied with the inter-prediction mode informationfrom the lossless decoding unit 132, the switch 145 supplies thepredictive image supplied from the motion compensation unit 144 to theaddition unit 135.

The chrominance signal inverse quantization unit 146 is configuredbasically in the same way as the chrominance signal inverse quantizationunit 51 in FIG. 9. The chrominance signal inverse quantization unit 146receives deltaQP, ΔQP_(C) and ChromaQPOffset from the lossless decodingunit 132. The chrominance signal inverse quantization unit 146calculates the predictive quantization parameter predQP from thequantization parameters of the adjacent CUs. The chrominance signalinverse quantization unit 146 reconstructs the luminance signalquantization parameter from deltaQP and predQP, and supplies thereconstructed luminance signal quantization parameter to the inversequantization unit 133.

The chrominance signal inverse quantization unit 146 reconstructs thechrominance signal quantization parameter from the reconstructedluminance signal quantization parameter, ΔQP_(C), and ChromaQPOffset,and supplies the reconstructed chrominance signal quantization parameterto the inverse quantization unit 133.

(Description of Series of Processing in Decoding Device)

FIG. 19 is a flowchart for explaining an image generation processing inthe decoding device 110 of FIG. 17.

In step S111 in FIG. 19, the reception unit 111 in the decoding device110 receives the coding stream transmitted from the coding device 10 ofFIG. 8, and supplies it to the extraction unit 112.

In step S112, the extraction unit 112 extracts the coding data and theparameter set from the coding stream supplied from the reception unit111, and supplies them to the decoding unit 113.

In step S113, the decoding unit 113 performs the decoding processing ofdecoding the coding data supplied from the extraction unit 112 in asystem conforming to the HEVC system by use of the parameter setsupplied from the extraction unit 112 as needed. The decoding processingwill be described below in detail with reference to FIG. 20. Theprocessing then ends.

FIG. 20 is a flowchart for explaining the decoding processing in stepS113 in FIG. 19 in detail.

In step S131 in FIG. 20, the accumulation buffer 131 (FIG. 18) in thedecoding unit 113 receives and accumulates the coding data in units offrame from the extraction unit 112 in FIG. 17. The accumulation buffer131 supplies the accumulated coding data to the lossless decoding unit132.

In step S132, the lossless decoding unit 132 losslessly decodes thecoding data from the accumulation buffer 131, and obtains thequantization value and the coding information. The lossless decodingunit 132 supplies the quantization value to the inverse quantizationunit 133. The lossless decoding unit 132 supplies deltaQP, ΔQP_(C), andChromaQPOffset as the coding information to the chrominance signalinverse quantization unit 146.

Further, the lossless decoding unit 132 supplies the intra-predictionmode information as the coding information to the intra-prediction unit143. The lossless decoding unit 132 supplies the motion vectors, theinter-prediction mode information, the reference image specificationinformation, and the like to the motion compensation unit 144.

Further, the lossless decoding unit 132 supplies the intra-predictionmode information or the inter-prediction mode information as the codinginformation to the switch 145. The lossless decoding unit 132 suppliesthe offset filter information as the coding information to the adaptiveoffset filter 137, and supplies the filter coefficient to the adaptiveloop filter 138.

In step S133, the chrominance signal inverse quantization unit 146performs the same quantization parameter reconstruction processing as inFIG. 16.

In the processing in step S133, the reconstructed luminance signalquantization parameter and chrominance signal quantization parameter aresupplied to the inverse quantization unit 133.

In step S134, the inverse quantization unit 133 inversely quantizes thequantization value supplied from the lossless decoding unit 132 by useof the luminance signal quantization parameter and the chrominancesignal quantization parameter from the chrominance signal inversequantization unit 146. The inverse quantization unit 133 supplies theorthogonal transform processing result obtained as a result of theinverse quantization to the inverse orthogonal transform unit 134.

In step S135, the inverse orthogonal transform unit 134 performs theorthogonal transform processing on the orthogonal transform processingresult from the inverse quantization unit 133.

In step S136, the motion compensation unit 144 determines whether theinter-prediction mode information is supplied from the lossless decodingunit 132. When it is determined in step S136 that the inter-predictionmode information is supplied, the processing proceeds to step S137.

In step S137, the motion compensation unit 144 reads the reference imagebased on the reference image specification information supplied from thelossless decoding unit 132, and performs the motion compensationprocessing in the optimum inter-prediction mode indicated by theinter-prediction mode information by use of the motion vectors and thereference image. The motion compensation unit 144 supplies the resultantpredictive image to the addition unit 135 via the switch 145, and theprocessing proceeds to step S139.

On the other hand, when it is determined in step S136 that theinter-prediction mode information is not supplied, or when theintra-prediction mode information is supplied to the intra-predictionunit 143, the processing proceeds to step S138.

In step S138, the intra-prediction unit 143 performs theintra-prediction processing in the intra-prediction mode indicated bythe intra-prediction mode information by use of the surrounding imagesread from the frame memory 141 via the switch 142. The intra-predictionunit 143 supplies the predictive image generated as a result of theintra-prediction processing to the addition unit 135 via the switch 145,and the processing proceeds to step S139.

In step S139, the addition unit 135 adds the residue informationsupplied from the inverse orthogonal transform unit 134 and thepredictive image supplied from the switch 145 thereby to performdecoding. The addition unit 135 supplies the decoded image to thedeblock filter 136 and the frame memory 141.

In step S140, the deblock filter 136 performs the deblocking filterprocessing on the image supplied from the addition unit 135 thereby toremove a block distortion. The deblock filter 136 supplies the resultantimage to the adaptive offset filter 137.

In step S141, the adaptive offset filter 137 performs the adaptiveoffset filter processing on the image subjected to the deblock filterprocessing by the deblock filter 136 per LCU based on the offset filterinformation supplied from the lossless decoding unit 132. The adaptiveoffset filter 137 supplies the image subjected to the adaptive offsetfilter processing to the adaptive loop filter 138.

In step S142, the adaptive loop filter 138 performs the adaptive loopfilter processing on the image supplied from the adaptive offset filter137 per LCU by use of the filter coefficient supplied from the losslessdecoding unit 132. The adaptive loop filter 138 supplies the resultantimage to the frame memory 141 and the screen rearrangement buffer 139.

In step S143, the frame memory 141 accumulates the image supplied fromthe addition unit 135 and the image supplied from the adaptive loopfilter 138. The images adjacent to PU, among the images which areaccumulated in the frame memory 141 and are not subjected to the filterprocessing, are supplied as surrounding images to the intra-predictionunit 143 via the switch 142. On the other hand, the images accumulatedin the frame memory 141 and subjected to the filter processing aresupplied as reference images to the motion compensation unit 144 via theswitch 142.

In step S144, the screen rearrangement buffer 139 stores the imagesupplied from the adaptive loop filter 138 in units of frame, andrearranges, in the original display order, the stored image in units offrame in the coding order, and supplies it to the D/A conversion unit140.

In step S145, the D/A conversion unit 140 D/A converts and outputs theimage in units of frame supplied from the screen rearrangement buffer139. The processing then returns to step S113 in FIG. 19, and ends.

As described above, ΔQPC is sent to the decoding side at the same timewith deltaQP, and thus the code amount of the chrominance signal in animage can be controlled also in the decoding device 110. In particular,even when a signal with wide color gamut is input, rate controllabilityfor chrominance signal can be enhanced.

As described above, the coding system employs a system conforming toHEVC. The present technique is not limited thereto, and can apply othercoding system/decoding system.

The present disclosure can be applied to an image coding device and animage decoding device used for receiving image information (bit stream)compressed by orthogonal transform such as discrete cosine transform andmotion compensation via a network medium such as satellite broadcasting,cable TV, Internet, or cell phone as in the HEVC system. Further, thepresent disclosure can be applied to an image coding device and an imagedecoding device used for the series of processing in a storage mediumsuch as optical disk, magnetic disk and flash memory.

Second Exemplary Embodiment

(Description of Computer to which the Present Disclosure is Applied)

The above series of processing can be realized in hardware or realizedin software. When the series of processing are realized in software, aprogram configuring the software is installed in the computer. Herein,the computer may be a computer incorporated in dedicated hardware, or ageneral-purpose personal computer capable of executing various functionsby installing various programs.

FIG. 21 is a block diagram illustrating an exemplary hardware structureof a computer for performing the series of processing by a program.

In the computer, central processing unit (CPU) 201, read only memory(ROM) 202, and random access memory (RAM) 203 are mutually connected viaa bus 204.

An I/O interface 205 is further connected to the bus 204. An input unit206, an output unit 207, a storage unit 208, a communication unit 209,and a drive 210 are connected to the I/O interface 205.

The input unit 206 is configured of keyboard, mouse, microphone, or thelike. The output unit 207 is configured of display, speaker, or thelike. The storage unit 208 is configured of a hard disk, a nonvolatilememory, or the like. The communication unit 209 is configured of anetwork interface or the like. The drive 210 drives a removable medium211 such as magnetic disk, optical disk, magnetooptical disk, orsemiconductor memory.

In the thus-configured computer, the CPU 201 loads and executes theprogram stored in the storage unit 208 into the RAM 203 via the I/Ointerface 205 and the bus 204 so that the series of processing areperformed.

The program executed by the computer (the CPU 201) can be recorded inthe removable medium 211 such as package medium to be provided. Further,the program can be provided via a wired or wireless transmission mediumsuch as local area network, Internet, or digital satellite broadcasting.

In the computer, the removable medium 211 is mounted on the drive 210 sothat the program can be installed in the storage unit 208 via the I/Ointerface 205. Further, the program can be received by the communicationunit 209 and installed in the storage unit 208 via a wired or wirelesstransmission medium. Additionally, the program can be previouslyinstalled in the ROM 202 or the storage unit 208.

The program executed by the computer may be a program in which theseries of processing are performed in time series in the order describedin the present specification, or a program in which the series ofprocessing are performed in parallel or at required timings such ascalling.

Third Exemplary Embodiment

(Application to Multi-View Image Coding and Multi-View Image Decoding)

The series of processing can be applied to multi-view image coding andmulti-view image decoding. FIG. 22 illustrates a multi-view image codingsystem by way of example.

As illustrated in FIG. 22, a multi-view image includes an image with aplurality of views. The views in the multi-view image are made of a baseview for coding and decoding by use of not the image of other view butonly the image of its own view and a non-base view for coding anddecoding by use of the image of other view. The non-base view may usethe image of a base view or may use the image of other non-base view.

When a multi-view image as illustrated in FIG. 22 is to be coded ordecoded, the image of each view is coded and decoded, but the methodaccording to the first exemplary embodiment may be applied to code ordecode each view. By doing so, the code amount of the chrominance signalin an image can be controlled. In particular, when a signal with widecolor gamut is input, rate controllability for chrominance signal can beenhanced.

Further, the parameters used in the method according to the firstexemplary embodiment may be shared for coding and decoding each view.More specifically, for example, the coding information such as deltaQP,ΔQPC, and ChromaQPOffset may be shared for coding and decoding eachview. Of course, other necessary information may be shared for codingand decoding each view.

By doing so, it is possible to prevent redundant information from beingtransmitted and to reduce the amount of information to be transmitted(the code amount) (or it is possible to prevent a reduction in codingefficiency).

(Multi-View Image Coding Device)

FIG. 23 is a diagram illustrating a multi-view image coding device forperforming the multi-view image coding. As illustrated in FIG. 23, amulti-view image coding device 600 has a coding unit 601, a coding unit602, and a multiplexing unit 603.

The coding unit 601 codes a base view image thereby to generate a baseview image coding stream. The coding unit 602 codes a non-base viewimage thereby to generate a non-base view image coding stream. Themultiplexing unit 603 multiplexes the base view image coding streamgenerated by the coding unit 601 and the non-base view image codingstream generated by the coding unit 602 thereby to generate a multi-viewimage coding stream.

The coding device 10 (FIG. 8) can be applied to the coding unit 601 andthe coding unit 602 in the multi-view image coding device 600. That is,the code amount of the chrominance signal in an image can be controlledfor coding each view. In particular, when a signal with wide color gamutis input, rate controllability for chrominance signal can be enhanced.Further, the coding unit 601 and the coding unit 602 can perform codingby use of the same flags or parameters (such as syntax elements forinter-image processing) (that is, can share the flags or parameters),thereby preventing a reduction in coding efficiency.

(Multi-View Image Decoding Device)

FIG. 24 is a diagram illustrating a multi-view image decoding device forperforming the multi-view image decoding. As illustrated in FIG. 24, amulti-view image decoding device 610 has a demultiplexing unit 611, adecoding unit 612, and a decoding unit 613.

The demultiplexing unit 611 demultiplexes the multi-view image codingstream in which the base view image coding stream and the non-base viewimage coding stream are multiplexed thereby to extract the base viewimage coding stream and the non-base view image coding stream. Thedecoding unit 612 decodes the base view image coding stream extracted bythe demultiplexing unit 611 thereby to obtain the base view image. Thedecoding unit 613 decodes the non-base view image coding streamextracted by the demultiplexing unit 611 to obtain the non-base viewimage.

The decoding device 110 (FIG. 17) can be applied to the decoding unit612 and the decoding unit 613 in the multi-view image decoding device610. That is, the code amount of the chrominance signal in an image canbe controlled for decoding each view. In particular, when a signal withwide color gamut is input, rate controllability for chrominance signalis enhanced thereby to decode a coding stream with enhanced codingefficiency. Further, the decoding unit 612 and the decoding unit 613 canperform decoding by use of the same flags or parameters (such as syntaxelements for inter-image processing) (or can share the flags orparameters), thereby preventing a reduction in coding efficiency.

Fourth Exemplary Embodiment

(Application to Hierarchy Image Coding and Hierarchy Image Decoding)

The series of processing can be applied for hierarchy image coding andhierarchy image decoding (scalable coding and scalable decoding). FIG.25 illustrates a hierarchy image coding system by way of example.

The hierarchy image coding (scalable coding) is directed for makingimage data into a plurality of layers (hierarchies) of images and codingeach layer in order to have a scalable function for predeterminedparameters. The hierarchy image decoding (scalable decoding) correspondsto the hierarchy image coding.

As illustrated in FIG. 25, for hierarchized image, one image is dividedinto a plurality of images (layers) with reference to a predeterminedparameter having the scalable function. That is, a hierarchized imageincludes a plurality of hierarchies (layers) of images havingmutually-different values of the predetermined parameter. The layers ofthe hierarchized images are made of a base layer for coding and decodingby use of not the images of other layers but only the image of its ownlayer and a non-base layer (also called enhancement layer) for codingand decoding by use of the image of other layer. The non-base layer mayuse the image of a base layer or may use the image of other non-baselayer.

Generally, the non-base layer is configured of differential image data(differential data) between its own image and the image of other layerin order to reduce redundancy. For example, when one image is made intotwo hierarchies of base layer and non-base layer (also calledenhancement layer), a lower-quality image than the original image isobtained by only the base layer data, and the original image (orhigher-quality image) is obtained by combining the base layer data andthe non-base layer data.

The image is made into hierarchies in this way thereby to easily obtainimages with various quality depending on a situation. Image compressioninformation of only the base layer is transmitted and animation with lowspatiotemporal resolution or low image quality is reproduced forterminals with low processing capability such as cell phone, and imagecompression information of the base layer and the enhancement layer istransmitted and animation with high spatiotemporal resolution or highimage quality is reproduced for terminals with high processingcapability such as TV or personal computer so that the image compressioninformation depending on the capability of a terminal or network can betransmitted from a server without the transcode processing.

When a hierarchy image as illustrated in the example of FIG. 25 is codedor decoded, the image of each layer is coded or decoded, and the methodaccording to the first exemplary embodiment may be applied for codingand decoding each layer. By doing so, the code amount of the chrominancesignal in an image can be controlled. In particular, when a signal withwide color gamut is input, rate controllability for chrominance signalcan be enhanced.

Further, the flags or parameters used in the method according to thefirst exemplary embodiment may be shared for coding and decoding eachlayer. More specifically, the coding information such as deltaQP, ΔQPC,and ChromaQPOffset may be shared for coding and decoding each layer. Ofcourse, other necessary information may be shared for coding anddecoding each layer.

By doing so, it is possible to prevent redundant information from beingtransmitted and to reduce the amount of information to be transmitted(the code amount) (or it is possible to prevent a reduction in codingefficiency).

(Scalable Parameters)

A parameter having the scalable function is optional for the hierarchyimage coding and the hierarchy image decoding (the scalable coding andthe scalable decoding). For example, a spatial resolution as illustratedin FIG. 26 may be assumed as a parameter (spatial scalability). In thecase of the spatial scalability, the resolution of an image is differentper layer. That is, in this case, as illustrated in FIG. 26, eachpicture is made into two hierarchies of the base layer with spatiallylower resolution than the original image and the enhancement layer withthe original spatial resolution in combination with the base layer. Ofcourse, the number of hierarchies is exemplary, and any number ofhierarchies may be possible.

A temporal resolution as illustrated in FIG. 27, for example, may beapplied (temporal scalability) as a parameter with the scalability. Inthe case of the temporal scalability, the frame rate is different perlayer. That is, in this case, as illustrated in FIG. 27, each picture ismade into two hierarchies of the base layer with a lower frame rate thanthe original animation and the enhancement layer with the original framerate in combination with the base layer. Of course, the number ofhierarchies is exemplary, and any number of hierarchies may be possible.

Further, signal to noise ratio (SNR) may be applied (SNR scalability),for example, as a parameter with the scalability. In the case of the SNRscalability, the SN ratio is different per layer. That is, in this case,as illustrated in FIG. 28, each picture is made into two hierarchies ofthe base layer with a lower SNR than the original image and theenhancement layer with the original SNR in combination with the baselayer. Of course, the number of hierarchies is exemplary, and any numberof hierarchies may be possible.

Parameters with the scalability other than the above examples may bepossible. For example, a bit depth can be employed (bit-depthscalability), for example, as a parameter with the scalability. In thecase of the bit-depth scalability, the bit depth is different per layer.In this case, for example, the base layer is made of an 8-bit image, andis added with the enhancement layer to be a 10-bit image.

A chroma format may be employed (chroma scalability) as a parameter withthe scalability. In the case of the chroma scalability, the chromaformat is different per layer. In this case, for example, the base layeris made of a component image with the 4:2:0 format, and is added withthe enhancement layer to be a component image with the 4:2:2 format.

(Hierarchy Image Coding Device)

FIG. 29 is a diagram illustrating a hierarchy image coding device forperforming the hierarchy image coding. As illustrated in FIG. 29, ahierarchy image coding device 620 has a coding unit 621, a coding unit622, and a multiplexing unit 623.

The coding unit 621 codes a base layer image thereby to generate a baselayer image coding stream. The coding unit 622 codes a non-base layerimage thereby to generate a non-base layer image coding stream. Themultiplexing unit 623 multiplexes the base layer image coding streamgenerated by the coding unit 621 and the non-base layer image codingstream generated by the coding unit 622 thereby to generate a hierarchyimage coding stream.

The coding device 10 (FIG. 8) can be applied to the coding unit 621 andthe coding unit 622 in the hierarchy image coding device 620. That is,the code amount of the chrominance signal in an image can be controlledfor coding each layer. In particular, when a signal with wide colorgamut is input, rate controllability for chrominance signal can beenhanced. Further, the coding unit 621 and the coding unit 622 cancontrol the intra-prediction filter processing by use of the same flagsor parameters (such as syntax elements for inter-image processing) (orcan share the flags or parameters), thereby preventing a reduction incoding efficiency.

(Hierarchy Image Decoding Device)

FIG. 30 is a diagram illustrating a hierarchy image decoding device forperforming the hierarchy image decoding. As illustrated in FIG. 30, ahierarchy image decoding device 630 has a demultiplexing unit 631, adecoding unit 632, and a decoding unit 633.

The demultiplexing unit 631 demultiplexes the hierarchy image codingstream in which the base layer image coding stream and the non-baselayer image coding stream are multiplexed thereby to extract the baselayer image coding stream and the non-base layer image coding stream.The decoding unit 632 decodes the base layer image coding streamextracted by the demultiplexing unit 631 thereby to obtain the baselayer image. The decoding unit 633 decodes the non-base layer imagecoding stream extracted by the demultiplexing unit 631 thereby to obtainthe non-base layer image.

The decoding device 110 (FIG. 17) can be applied to the decoding unit632 and the decoding unit 633 in the hierarchy image decoding device630. That is, the code amount of the chrominance signal in an image canbe controlled for decoding each layer. When a signal with wide colorgamut is input, rate controllability for chrominance signal is enhancedthereby to decode a coding stream with enhanced coding efficiency.Further, the decoding unit 612 and the decoding unit 613 can performdecoding by use of the same flags or parameters (such as syntax elementsfor inter-image processing) (or can share the flags or parameters),thereby preventing a reduction in coding efficiency.

Fifth Exemplary Embodiment

(Exemplary Structure of TV Set)

FIG. 31 illustrates an exemplary schematic structure of a TV set towhich the present disclosure is applied. A TV set 900 has an antenna901, a tuner 902, a demultiplexer 903, a decoder 904, a video signalprocessing unit 905, a display unit 906, a speech signal processing unit907, a speaker 908, and an external interface unit 909. The TV set 900further has a control unit 910, and a user interface unit 911.

The tuner 902 selects and demodulates a desired channel based on abroadcasting signal received by the antenna 901, and outputs theresultant coding bit stream to the demultiplexer 903.

The demultiplexer 903 extracts the packets of video or speech of aprogram to be viewed from the coding bit stream and outputs theextracted packet data to the decoder 904. Further, the demultiplexer 903supplies the packets of the data such as electronic program guide (EPG)to the control unit 910. While scrambling is performed, descrambling isperformed by the demultiplexer or the like.

The decoder 904 performs a packet decoding processing, and outputs thevideo data generated by the decoding processing to the video signalprocessing unit 905, and the speech data to the speech signal processingunit 907.

The video signal processing unit 905 performs a video processing or thelike on the video data depending on noise removal or user setting. Thevideo signal processing unit 905 generates the video data of a programto be displayed by the display unit 906, or image data by the processingbased on an application supplied via a network. Further, the videosignal processing unit 905 generates the video data for displaying amenu screen or the like for item selection, and superimposes it on thevideo data of the program. The video signal processing unit 905generates a drive signal based on the thus-generated video data therebyto drive the display unit 906.

The display unit 906 drives a display device (such as liquid crystaldisplay device) based on the drive signal from the video signalprocessing unit 905 thereby to display the video of the program.

The speech signal processing unit 907 performs a predeterminedprocessing such as noise removal on the speech data, performs a D/Aconversion processing or amplification processing on the processedspeech data to be supplied to the speaker 908, thereby performing speechoutput.

The external interface unit 909 is an interface for connecting to anexternal device or network, and exchanges data such as video data orspeech data.

The user interface unit 911 is connected to the control unit 910. Theuser interface unit 911 is configured of an operation switch, a remotecontrol signal reception unit, or the like, and supplies an operationsignal in response to a user operation to the control unit 910.

The control unit 910 is configured of central processing unit (CPU), amemory, or the like. The memory stores therein the programs executed bythe CPU, various items of data required for the series of processing ofthe CPU, EPG data, data obtained via a network, and the like. Theprogram stored in the memory is read and executed by the CPU at apredetermined timing such as startup of the TV set 900. The CPU executesthe program so that the TV set 900 controls each unit to operate inresponse to a user operation.

The TV set 900 is provided with a bus 912 for connecting the tuner 902,the demultiplexer 903, the video signal processing unit 905, the speechsignal processing unit 907, the external interface unit 909, and thelike to the control unit 910.

In the thus-configured TV set, the decoder 904 is provided with thefunctions of the decoding device (decoding method) according to thepresent application. Thus, the code amount of the chrominance signal inan image can be controlled in the coding stream decoding processing. Inparticular, when a signal with wide color gamut is input, ratecontrollability for chrominance signal can be enhanced.

Sixth Exemplary Embodiment

(Exemplary Structure of Cell Phone)

FIG. 32 illustrates an exemplary schematic structure of a cell phone towhich the present disclosure is applied. A cell phone 920 has acommunication unit 922, a speech codec 923, a camera unit 926, an imageprocessing unit 927, a multiplexing/separating unit 928, arecording/reproducing unit 929, a display unit 930, and a control unit931. These are mutually connected via a bus 933.

Further, an antenna 921 is connected to the communication unit 922, anda speaker 924 and a microphone 925 are connected to the speech codec923. Further, an operation unit 932 is connected to the control unit931.

The cell phone 920 performs various operations such as exchanging speechsignals, exchanging e-mails or image data, shooting images, or recordingdata in various modes such as speech call mode and data communicationmode.

In the speech call mode, a speech signal generated by the microphone 925is converted into speech data by the speech codec 923 or subjected todata compression to be supplied to the communication unit 922. Thecommunication unit 922 performs a modulation processing or a frequencyconversion processing on the speech data thereby to generate atransmission signal. Further, the communication unit 922 supplies thetransmission signal to the antenna 921 to be transmitted to a basestation (not illustrated). Further, the communication unit 922 amplifiesthe reception signal received by the antenna 921 or performs thefrequency conversion processing and a demodulation processing thereonthereby to supply the resultant speech data to the speech codec 923. Thespeech codec 923 extends the speech data or converts it into an analogspeech signal to be output to the speaker 924.

Further, when an e-mail is transmitted in the data communication mode,the control unit 931 receives character data input by an operation ofthe operation unit 932, and displays the input characters on the displayunit 930. Further, the control unit 931 generates e-mail data based on auser instruction or the like via the operation unit 932 to be suppliedto the communication unit 922. The communication unit 922 performs themodulation processing or the frequency conversion processing on thee-mail data, and transmits the resultant transmission signal from theantenna 921. Further, the communication unit 922 amplifies the receptionsignal received by the antenna 921 or performs the frequency conversionprocessing and the demodulation processing thereon thereby to recoverthe e-mail data. The e-mail data is supplied to the display unit 930thereby to display the e-mail contents.

The cell phone 920 can store the received e-mail data in a storagemedium by the recording/reproducing unit 929. The storage medium is arewritable storage medium. For example, the storage medium is asemiconductor memory such as RAM or incorporated flash memory, or aremovable medium such as hard disk, magnetic disk, magnetooptical disk,optical disk, universal serial bus (USB) memory, or memory card.

When image data is transmitted in the data communication mode, imagedata generated by the camera unit 926 is supplied to the imageprocessing unit 927. The image processing unit 927 performs the codingprocessing on the image data thereby to generate coding data.

The multiplexing/separating unit 928 multiplexes the coding datagenerated by the image processing unit 927 and the speech data suppliedfrom the speech codec 923 in a predetermined system to be supplied tothe communication unit 922. The communication unit 922 performs themodulation processing or the frequency conversion processing on themultiplexed data, and transmits the resultant transmission signal fromthe antenna 921. Further, the communication unit 922 amplifies thereception signal received by the antenna 921 or performs the frequencyconversion processing and the demodulation processing thereon thereby torecover the multiplexed data. The multiplexed data is supplied to themultiplexing/separating unit 928. The multiplexing/separating unit 928separates the multiplexed data, and supplies the coding data to theimage processing unit 927, and the speech data to the speech codec 923.The image processing unit 927 performs the decoding processing on thecoding data thereby to generate the image data. The image data issupplied to the display unit 930 thereby to display the received image.The speech codec 923 converts the speech data into an analog speechsignal to be supplied to the speaker 924, thereby outputting thereceived speech.

In the thus-configured cell phone, the image processing unit 927 isprovided with the functions of the coding device and the decoding device(the coding method and the decoding method) according to the presentapplication. Therefore, the code amount of the chrominance signal in animage can be controlled. In particular, when a signal with wide colorgamut is input, rate controllability for chrominance signal can beenhanced.

Seventh Exemplary Embodiment

(Exemplary Structure of Recording/Reproducing Device)

FIG. 33 illustrates an exemplary schematic structure of arecording/reproducing device to which the present disclosure is applied.A recording/reproducing device 940 records audio data and video data ofa received broadcast program, for example, in a recording medium, andsupplies the recorded data to the user at a user-instructed timing.Further, the recording/reproducing device 940 can obtain audio data orvideo data from other device, for example, and can record it in arecording medium. Furthermore, the recording/reproducing device 940decodes and outputs the audio data or the video data recorded in therecoding medium thereby to perform image display or speech output in amonitor device or the like.

The recording/reproducing device 940 has a tuner 941, an externalinterface unit 942, an encoder 943, a hard disk drive (HDD) unit 944, adisk drive 945, a selector 946, a decoder 947, an on-screen display(OSD) unit 948, a control unit 949, and a user interface unit 950.

The tuner 941 selects a desired channel based on a broadcast signalreceived by an antenna (not illustrated). The tuner 941 outputs a codingbit stream obtained by demodulating the reception signal of the desiredchannel to the selector 946.

The external interface unit 942 is configured of at least one ofIEEE1394 interface, network interface unit, USB interface, and flashmemory interface. The external interface unit 942 is an interface forconnecting to an external device, a network, a memory card, or the like,and receives data such as video data or speech data to be recorded.

The encoder 943 codes the video data or the speech data supplied fromthe external interface unit 942 in a predetermined system, if not coded,and outputs a coding bit stream to the selector 946.

The HDD unit 944 records content data such as video or speech, variousprograms, other data, and the like in the incorporated hard disk, andreads them from the hard disk on reproduction or the like.

The disk drive 945 records and reproduces the signals on the mountedoptical disk. It is an optical disk, a DVD disk (such as DVD-Video,DVD-RAM, DVD-R, DVD-RW, DVD+R or DVD+RW), or a Blu-ray (registeredtrademark) disk, for example.

The selector 946 selects the coding bit stream of either the tuner 941or the encoder 943 when recording video or speech, and supplies it toeither the HDD unit 944 or the disk drive 945. Further, the selector 946supplies the coding bit stream output from the HDD unit 944 or the diskdrive 945 to the decoder 947 when reproducing video or speech.

The decoder 947 performs the decoding processing on the coding bitstream. The decoder 947 supplies the video data generated by thedecoding processing to the OSD unit 948. Further, the decoder 947outputs the speech data generated by the decoding processing.

The OSD unit 948 generates the video data for displaying a menu screenor the like for item selection, and superimposes and outputs it on thevideo data output from the decoder 947.

The user interface unit 950 is connected to the control unit 949. Theuser interface unit 950 is configured of an operation switch, a remotecontrol signal reception unit, or the like, and supplies an operationsignal in response to a user operation to the control unit 949.

The control unit 949 is configured of CPU, a memory, or the like. Thememory stores the programs executed by the CPU or various items of datarequired for the series of processing by the CPU. The program stored inthe memory is read and executed by the CPU at a predetermined timingsuch as startup of the recording/reproducing device 940. The CPUexecutes the program so that the recording/reproducing device 940controls each unit to operate depending on a user operation.

In the thus-configured recording/reproducing device, the decoder 947 isprovided with the functions of the decoding device (the decoding method)according to the present application. Therefore, the code amount of thechrominance signal in an image can be controlled for deciding a codingstream. In particular, when a signal with wide color gamut is input,rate controllability for chrominance signal can be enhanced.

Eighth Exemplary Embodiment

(Exemplary Structure of Imaging Device)

FIG. 34 illustrates an exemplary schematic structure of an imagingdevice to which the present disclosure is applied. An imaging device 960shoots a subject to display the image of the subject on a display unitor records it as image data in a recording medium.

The imaging device 960 has an optical block 961, an imaging unit 962, acamera signal processing unit 963, an image data processing unit 964, adisplay unit 965, an external interface unit 966, a memory unit 967, amedium drive 968, an OSD unit 969, and a control unit 970. A userinterface unit 971 is connected to the control unit 970. Further, theimage data processing unit 964, the external interface unit 966, thememory unit 967, the medium drive 968, the OSD unit 969, the controlunit 970, and the like are mutually connected via a bus 972.

The optical block 961 is configured of a focus lens, a diaphragmmechanism, or the like. The optical block 961 forms an optical image ofa subject on the imaging face of the imaging unit 962. The imaging unit962 is configured of a CCD or CMOS image sensor, generates an electricsignal depending on an optical image by photoelectric conversion andsupplies it to the camera signal processing unit 963.

The camera signal processing unit 963 performs various camera signalprocessing such as knee correction, gamma correction, and colorcorrection on the electric signal supplied from the imaging unit 962.The camera signal processing unit 963 supplies the image data subjectedto the camera signal processing to the image data processing unit 964.

The image data processing unit 964 performs a coding processing on theimage data supplied from the camera signal processing unit 963. Theimage data processing unit 964 supplies coding data generated by thecoding processing to the external interface unit 966 or the medium drive968. Further, the image data processing unit 964 performs a decodingprocessing on the coding data supplied from the external interface unit966 or the medium drive 968. The image data processing unit 964 suppliesthe image data generated by the decoding processing to the display unit965. Further, the image data processing unit 964 performs the processingof supplying the image data supplied from the camera signal processingunit 963 to the display unit 965, or superimposes the display dataobtained from the OSD unit 969 on the image data to be supplied to thedisplay unit 965.

The OSD unit 969 generates display data such as menu scree or icons madeof symbols, characters or graphics, and outputs it to the image dataprocessing unit 964.

The external interface unit 966 is configured of a USB I/O terminal orthe like, for example, and is connected to a printer when printing animage. Further, a drive is connected to the external interface unit 966as needed, a removable medium such as magnetic disk or optical disk ismounted thereon as needs, and a computer program read therefrom isinstalled as needed. Further, the external interface unit 966 has anetwork interface connected to a predetermined network such as LAN orInternet. The control unit 970 can read the coding data from the mediumdrive 968 in response to an instruction from the user interface unit971, for example, and can supply it from the external interface unit 966to other device connected via a network. Further, the control unit 970can obtain coding data or image data supplied from other device via anetwork by the external interface unit 966, and can supply it to theimage data processing unit 964.

The recoding medium driven by the medium drive 968 may be any rewritableremovable medium such as magnetic disk, magnetooptical disk, opticaldisk, or semiconductor memory. The recording medium may be any type ofremovable medium, a tape device, a disk, or a memory card. Of course, itmay be a non-contact integrated circuit (IC) card or the like.

Further, the medium drive 968 and a recording medium may be integratedto be configured in a non-portable storage medium such as incorporatedhard disk drive or solid state drive (SSD).

The control unit 970 is configured of CPU. The memory unit 967 storesprograms executed by the control unit 970, or various items of datarequired for the series of processing by the control unit 970. Theprogram stored in the memory unit 967 is read and executed by thecontrol unit 970 at a predetermined timing such as startup of theimaging device 960. The control unit 970 executes the programs therebyto control each unit such that the imaging device 960 operates inresponse to a user operation.

In the thus-configured imaging device, the image data processing unit964 is provided with the functions of the coding device and the decodingdevice (the coding method and the decoding method) according to thepresent application. Therefore, the code amount of the chrominancesignal in an image can be controlled for coding or decoding a codingstream. In particular, when a signal with wide color gamut is input,rate controllability for chrominance signal can be enhanced.

<Exemplary Applications of Scalable Coding>

(First System)

Specific exemplary use of scalable coding data subjected to the scalablecoding (hierarchy coding) will be described below. The scalable codingis used for selecting data to be transmitted as in the exampleillustrated in FIG. 35, for example.

In a data transmission system 1000 illustrated in FIG. 35, adistribution server 1002 reads scalable coding data stored in a scalablecoding data storage unit 1001, and distributes it to terminal devicessuch as a personal computer 1004, an AV device 1005, a tablet device1006, and a cell phone 1007 via a network 1003.

At this time, the distribution server 1002 selects and transmits thecoding data with appropriate quality depending on the capability orcommunication environment of a terminal device. Even when thedistribution server 1002 transmits data with unnecessarily high quality,a high-quality image cannot be necessarily obtained in the terminaldevice, which can be a cause for delay or overflow. Further, acommunication bandwidth can be unnecessarily occupied or loads on theterminal device can be unnecessarily increased. Inversely, even when thedistribution server 1002 transmits data with unnecessarily low quality,an image with sufficient quality cannot be obtained in the terminaldevice. Therefore, the distribution server 1002 reads and transmits thescalable coding data stored in the scalable coding data storage unit1001 as coding data with appropriate quality for the capability orcommunication environment of a terminal device as needed.

For example, the scalable coding data storage unit 1001 is assumed tostore scalable coding data (BL+EL) 1011 subjected to scalable coding.The scalable coding data (BL+EL) 1011 is coding data including both thebase layer and the enhancement layer, and is data capable of obtainingboth the base layer image and the enhancement layer image when beingdecoded.

The distribution server 1002 selects an appropriate layer and reads thedata of the layer depending on the capability or communicationenvironment of a terminal device to which the data is to be transmitted.For example, the distribution server 1002 reads and transmits thehigh-quality scalable coding data (BL+EL) 1011 from the scalable codingdata storage unit 1001 to the personal computer 1004 or the tabletdevice 1006 with high processing capability. To the contrary, forexample, the distribution server 1002 extracts the data of the baselayer from the scalable coding data (BL+EL) 1011, and transmits it aslower-quality scalable coding data (BL) 1012 than the scalable codingdata (BL+EL) 1011, which has the same contents as the scalable codingdata (BL+EL) 1011, to the AV device 1005 or the cell phone 1007 with lowprocessing capability.

The amount of data can be easily adjusted by use of the scalable codingdata in this way, thereby preventing delay or overflow from occurring,or preventing an unnecessary increase in loads on the terminal device orcommunication medium. Further, the scalable coding data (BL+EL) 1011 isreduced in redundancy between layers, and thus the amount of data can befurther reduced than when the coding data of each layer is assumed asindividual item of data. Therefore, the storage area in the scalablecoding data storage unit 1001 can be more efficiently used.

Various devices can be applied to the terminal devices such as thepersonal computer 1004 to the cell phone 1007, and thus the hardwareperformance of a terminal device is different per device. Further,various applications are executed by the terminal devices, and thecapability of the software is also different. Further, any communicationline networks including wired, wireless or both networks such asInternet or local area network (LAN) can be applied to the network 1003as communication medium, and the data transmission capability isdifferent. Further, it can be changed due to other communication.

Thus, the distribution server 1002 may make communication with aterminal device as data transmission destination before starting totransmit data, and may obtain the information on the capability of theterminal device such as hardware performance of the terminal device orthe performance of application (software) executed by the terminaldevice, as well as the information on the communication environment suchas available bandwidth to the network 1003. The distribution server 1002may select an appropriate layer based on the obtained information.

A layer may be extracted in a terminal device. For example, the personalcomputer 1004 may decode the transmitted scalable coding data (BL+EL)1011 thereby to display the base layer image, or to display theenhancement layer image. Further, for example, the personal computer1004 may extract, store, or transfer the scalable coding data (BL) 1012of the base layer from the transmitted scalable coding data (BL+EL) 1011to other device, or decode it thereby to display the base layer image.

Of course, any numbers of scalable coding data storage units 1001,distribution servers 1002, networks 1003, and terminal devices may bepossible. Further, there has been described above the example in whichthe distribution server 1002 transmits data to a terminal device, butthe exemplary use is not limited thereto. The data transmission system1000 can be applied to any system for selecting and transmitting anappropriate layer depending on the capability or communicationenvironment of a terminal device when transmitting coding data subjectedto the scalable coding to the terminal device.

(Second System)

The scalable coding is used for transmission via a plurality ofcommunication mediums as in the example illustrated in FIG. 36, forexample.

In a data transmission system 1100 illustrated in FIG. 36, a broadcaststation 1101 transmits scalable coding data (BL) 1121 of the base layervia terrestrial broadcasting 1111. Further, the broadcast station 1101transmits (packetizes and transmits, for example) scalable coding data(EL) 1122 of the enhancement layer via any networks 1112 includingwired, wireless, or both communication networks.

A terminal device 1102 has a reception function of the terrestrialbroadcasting 1111 broadcasted by the broadcast station 1101, andreceives the scalable coding data (BL) 1121 of the base layertransmitted via the terrestrial broadcasting 1111. Further, the terminaldevice 1102 further has a communication function of making communicationvia the network 1112, and receives the scalable coding data (EL) 1122 ofthe enhancement layer transmitted via the network 1112.

The terminal device 1102 decodes the scalable coding data (BL) 1121 ofthe base layer obtained via the terrestrial broadcasting 1111 inresponse to a user instruction, for example, thereby to obtain, store ortransfer the base layer image to other device.

Further, the terminal device 1102 combines the scalable coding data (BL)1121 of the base layer obtained via the terrestrial broadcasting 1111and the scalable coding data (EL) 1122 of the enhancement layer obtainedvia the network 1112 in response to a user instruction, for example,thereby to obtain scalable coding data (BL+EL), or decodes them therebyto obtain, store or transfer the enhancement layer image to otherdevice.

As described above, the scalable coding data can be transmitted via adifferent communication medium per layer, for example. Therefore, it ispossible to disperse loads and to prevent delay or overflow fromoccurring.

A communication medium to be used for transmission can be selected perlayer depending on a situation. For example, the scalable coding data(BL) 1121 of the base layer with a relatively large amount of data maybe transmitted via a communication medium with a large bandwidth, andthe scalable coding data (EL) 1122 of the enhancement layer with arelatively small amount of data may be transmitted via a communicationmedium with a small bandwidth. Further, for example, a communicationmedium for transmitting the scalable coding data (EL) 1122 of theenhancement layer may be switched to the network 1112 or the terrestrialbroadcasting 1111 depending on an available bandwidth to the network1112. Of course, this is applicable to data of any layer.

It is possible to further prevent an increase in loads in datatransmission under the control.

Of course, any number of layers may be possible, and any number ofcommunication mediums used for transmission may be possible. Further,any number of terminal devices 1102 as data distribution destinationsmay be also possible. The description has been made above assuming thebroadcasting from the broadcast station 1101, but the exemplary use isnot limited thereto. The data transmission system 1100 can be applied toany system for dividing coding data subjected to the scalable codinginto a plurality of items of data in units of layer and transmittingthem via a plurality of lines.

(Third System)

The scalable coding is used for storing coding data as in the exampleillustrated in FIG. 37, for example.

In an imaging system 1200 illustrated in FIG. 37, an imaging device 1201performs scalable coding on image data obtained by shooting a subject1211, and supplies it as scalable coding data (BL+EL) 1221 to a scalablecoding data storage device 1202.

The scalable coding data storage device 1202 stores the scalable codingdata (BL+EL) 1221 supplied from the imaging device 1201 atsituation-dependent quality. For example, during a normal time, thescalable coding data storage device 1202 extracts the data of the baselayer from the scalable coding data (BL+EL) 1221 and stores it asscalable coding data (BL) 1222 of the base layer with low quality and asmall amount of data. To the contrary, for example, during a time ofinterest, the scalable coding data storage device 1202 stores thescalable coding data (BL+EL) 1221 with high quality and a large amountof data as it is.

By doing so, the scalable coding data storage device 1202 can store theimage at high quality as needed, thereby preventing an increase in dataand enhancing use efficiency in the storage area while preventing areduction in value of the image due to deteriorated image quality.

For example, the imaging device 1201 is assumed as a monitoring camera.When an object to be monitored (such as intruder) is not shot in a shotimage (during a normal time), the contents of the shot image are lesslikely to be important, and thus a reduction in data is prior and theimage data (scalable coding data) is stored at low quality. To thecontrary, when an object to be monitored is shot as the subject 1211 ina shot image (during a time of interest), the contents of the shot imageare likely to be important, and thus the image quality is prior and theimage data (scalable coding data) is stored at high quality.

A normal time or a time of interest may be determined by the scalablecoding data storage device 1202 analyzing an image, for example.Further, it may be determined by the imaging device 1201 and adetermination result may be transmitted to the scalable coding datastorage device 1202.

A determination reference for a normal time and a time of interest isoptional, and the contents of an image as determination reference areoptional. Of course, the conditions other than the contents of an imagemay be assumed as determination reference. For example, the time may beswitched depending on magnitude or waveform of recorded speech, may beswitched per predetermined time, or may be switched in response to anexternal instruction such as user instruction.

There has been described above the example in which two states of anormal time and a time of interest are switched, but any number ofstates may be possible, and three or more states such as normal time,time of slight interest, time of interest, and time of strong interestmay be switched, for example. The upper limit number of states to beswitched depends on the number of layers of the scalable coding data.

Further, the imaging device 1201 may determine the number of layers ofthe scalable coding depending on a state. For example, during a normaltime, the imaging device 1201 may generate the scalable coding data (BL)1222 of the base layer with low quality and a small amount of data andsupply it to the scalable coding data storage device 1202.

Further, for example, during a time of interest, the imaging device 1201may generate the scalable coding data (BL+EL) 1221 of the base layerwith high quality and a large amount of data and supply it to thescalable coding data storage device 1202.

The description has been made above by way of a monitoring camera, butthe imaging system 1200 is arbitrarily used and is not limited to amonitoring camera.

Ninth Exemplary Embodiment Other Exemplary Embodiments

The devices or systems to which the present disclosure is applied havebeen described above by way of example, but the present disclosure isnot limited thereto and may be accomplished in all the structuresemployed in the devices configuring such devices or systems, such asprocessors as system large scale integration (LSI), modules using aplurality of processors, units using a plurality of models, sets ofunits added with other functions (partial structure in the device).

(Exemplary Structure of Video Set)

An example in which the present disclosure is accomplished as a set willbe described with reference to FIG. 38. FIG. 38 illustrates an exemplaryschematic structure of a video set to which the present disclosure isapplied.

In recent years, multifunctional electronic devices have been increased,and when some components thereof are sold or provided in theirdevelopment or manufacture, a structure having one function isaccomplished, and additionally a plurality of components havingassociated functions are combined to be accomplished as a set offunctions in more cases.

A video set 1300 illustrated in FIG. 38 is configured to bemultifunctional, and is such that a device having the functions of(either one or both of) coding and decoding an image is combined with adevice having other functions associated with the functions.

As illustrated in FIG. 38, the video set 1300 has a group of modulessuch as a video module 1311, an external memory 1312, a power managementmodule 1313, and a frontend module 1314, and devices having theassociated functions such as connectivity 1321, a camera 1322, and asensor 1323.

A module is a component in which some mutually-associated componentfunctions are collected to have a collective function. A specificphysical configuration is optional, and there is assumed such that aplurality of processors having the respective functions, electroniccircuit devices such as resistors or capacitors, and other devices arearranged and integrated on a wiring board or the like. Further, there isassumed such that other modules or processors are combined with a modulethereby to be a new module.

In the example of FIG. 38, the video module 1311 is a combination of thecomponents having the functions for the image processing, which has anapplication processor, a video processor, a broadband modem 1333, and aRF module 1334.

A processor is such that a component having a predetermined function isintegrated on a semiconductor chip by system on a chip (SoC), and iscalled system large scale integration (LSI) or the like. The componenthaving a predetermined function may be a logic circuit (hardwareconfiguration), may be CPU, ROM, RAM and a program (softwareconfiguration) executed by them, or may be a combination of both. Forexample, the processor may have the logic circuit as well as CPU, ROM,RAM and the like, and some functions may be realized in a logic circuit(hardware configuration) while other functions may be realized by theprograms (software configuration) executed by the CPU.

The application processor 1331 of FIG. 38 is a processor for executingthe image processing application. The application executed by theapplication processor 1331 can perform a computation processing forrealizing the predetermined function, and additionally control thecomponents inside and outside the video module 1311, such as the videoprocessor 1332, as needed.

The video processor 1332 is a processor having the functions of (eitherone or both of) coding and decoding an image.

The broadband modem 1333 is a processor (or module) for performing aprocessing for (either one or both of) wired and wireless wide bandcommunications made via a wide band line such as Internet or publicphone line network. For example, the broadband modem 1333 converts data(digital signal) to be transmitted into an analog signal by digitalmodulation or the like, or demodulates and converts a received analogsignal into data (digital signal). For example, the broadband modem 1333can perform digital modulation and demodulation on any information suchas image data processed by the video processor 1332, stream of codedimage data, application program or setting data.

The RF module 1334 is a module for performing frequency conversion,modulation/demodulation, amplification, filter processing, and the likeon a radio frequency (RF) signal exchanged via an antenna. For example,the RF module 1334 performs frequency conversion or the like on abaseband signal generated by the broadband modem 1333 thereby togenerate a RF signal. Further, for example, the RF module 1334 performsfrequency conversion or the like on a RF signal received via thefrontend module 1314 thereby to generate a baseband signal.

As indicated in a dotted line 1341 in FIG. 38, the application processor1331 and the video processor 1332 may be integrated to be configured asone processor.

The external memory 1312 is a module having a storage device used by thevideo module 1311, which is provided outside the video module 1311. Thestorage device for the external memory 1312 may be realized by anyphysical configuration, but is desirably realized in a relatively-lowcost semiconductor memory with a large capacity such as dynamic randomaccess memory (DRAM) since it is generally used for storing a largecapacity of data such as image data in units of frame in many cases.

The power management module 1313 manages and controls power supplying tothe video module 1311 (each component in the video module 1311).

The frontend module 1314 is a module for providing a frontend function(circuit at the exchange end on the antenna side) for the RF module1334. As illustrated in FIG. 38, the frontend module 1314 has an antennaunit 1351, a filter 1352, and an amplification unit 1353, for example.

The antenna unit 1351 has an antenna for exchanging wireless signals,and its surrounding components. The antenna unit 1351 transmits a signalsupplied from the amplification unit 1353 as wireless signal, andsupplies a received wireless signal as electric signal (RF signal) tothe filter 1352. The filter 1352 performs a filter processing or thelike on the RF signal received via the antenna unit 1351, and suppliesthe processed RF signal to the RF module 1334. The amplification unit1353 amplifies the RF signal supplied from the RF module 1334, andsupplies it to the antenna unit 1351.

The connectivity 1321 is a module having the function for externalconnection. The physical configuration of the connectivity 1321 isoptional. For example, the connectivity 1321 has a configuration havingthe communication function other than communication standard to whichthe broadband modem 1333 corresponds, an external I/O terminal, and thelike.

For example, the connectivity 1321 may have a module having thecommunication function conforming to wireless communication standardsuch as Bluetooth (registered trademark), IEEE 802.11 (such as WirelessFidelity (Wi-Fi, registered trademark)), near field communication (NFC),and infrared data association (IrDA), an antenna for exchanging signalsconforming to the standard, and the like. Further, for example, theconnectivity 1321 may have a module having the communication functionconforming to wired communication standard such as universal serial bus(USB) and High-Definition Multimedia Interface (registered trademark)(HDMI), or a terminal conforming to the standard. Furthermore, forexample, the connectivity 1321 may have other data (signal) transmissionfunction such as analog I/O terminal.

The connectivity 1321 may include a device of data (signal) transmissiondestination. For example, the connectivity 1321 may have a drive forreading or writing data from or into a recording medium such as magneticdisk, optical, disk, magnetooptical disk, or semiconductor memory(including not only a removable medium drive but also hard disk, solidstate drive (SSD), and network attached storage (NAS)). Further, theconnectivity 1321 may have a device for outputting images or speech(such as monitor or speaker).

The camera 1322 is a module having the function of imaging a subject andobtaining image data of the subject. The image data obtained by theimaging of the camera 1322 is supplied to the video processor 1332 to becoded, for example.

The sensor 1323 is a module having any sensor function such as speechsensor, ultrasonic sensor, optical sensor, illumination sensor, infraredsensor, image sensor, rotation sensor, angle sensor, angular velocitysensor, velocity sensor, acceleration sensor, tilt sensor, magneticidentification sensor, collision sensor, or temperature sensor. Datadetected by the sensor 1323 is supplied to the application processor1331 to be used by the application or the like.

The components described above as modules may be realized as processors,or the components described as processors may be realized as modules.

In the thus-configured video set 1300, the present disclosure can beapplied to the video processor 1332 as described below. Thus, the videoset 1300 can be accomplished as a set to which the present disclosure isapplied.

(Exemplary Structure of Video Processor)

FIG. 39 illustrates an exemplary schematic structure of the videoprocessor 1332 (FIG. 38) to which the present disclosure is applied.

In the example of FIG. 39, the video processor 1332 has a function ofreceiving an input video signal and audio signal and coding them in apredetermined system, and a function of decoding coded video data andaudio data and reproducing and outputting a video signal and an audiosignal.

As illustrated in FIG. 39, the video processor 1332 has a video inputprocessing unit 1401, a first image enlargement/reduction unit 1402, asecond image enlargement/reduction unit 1403, a video output processingunit 1404, a frame memory 1405, and a memory control unit 1406. Thevideo processor 1332 further has an encode/decode engine 1407, videoelementary stream (ES) buffers 1408A and 1408B, and audio ES buffers1409A and 1409B. The video processor 1332 further has an audio encoder1410, an audio decoder 1411, a multiplexing unit (Multiplexer (MUX))1412, a demultiplexing unit (Demultiplexer (DMUX)) 1413, and a streambuffer 1414.

The video input processing unit 1401 obtains a video signal input by theconnectivity 1321 (FIG. 38) or the like, for example, and converts itinto digital image data. The first image enlargement/reduction unit 1402performs format conversion or image enlargement/reduction processing onthe image data. The second image enlargement/reduction unit 1403performs an image enlargement/reduction processing on the image datadepending on a format of an output destination via the video outputprocessing unit 1404, or performs the format conversion or the imageenlargement/reduction processing similarly to the first imageenlargement/reduction unit 1402. The video output processing unit 1404performs format conversion on the image data or converts it into ananalog signal, and outputs it as reproduced video signal to theconnectivity 1321 (FIG. 38) or the like, for example.

The frame memory 1405 is a memory for image data shared among the videoinput processing unit 1401, the first image enlargement/reduction unit1402, the second image enlargement/reduction unit 1403, the video outputprocessing unit 1404, and the encode/decode engine 1407. The framememory 1405 is realized as a semiconductor memory such as DRAM.

The memory control unit 1406 controls to write/read into/from the framememory 1405 according to an access schedule to the frame memory 1405written in an access management table 1406A in response to asynchronization signal from the encode/decode engine 1407. The accessmanagement table 1406A is updated by the memory control unit 1406depending on the series of processing performed by the encode/decodeengine 1407, the first image enlargement/reduction unit 1402, the secondimage enlargement/reduction unit 1403, and the like.

The encode/decode engine 1407 performs an encode processing on the imagedata, and perform a decode processing on a video stream as coded imagedata. For example, the encode/decode engine 1407 codes the image readfrom the frame memory 1405, and sequentially writes it as video streaminto the video ES buffer 1408A. Further, for example, the video streamsare sequentially read and decoded from the video ES buffer 1408B and aresequentially written as image data into the frame memory 1405. Theencode/decode engine 1407 uses the frame memory 1405 as working area forthe coding or decoding. Further, the encode/decode engine 1407 outputs asynchronization signal to the memory control unit 1406 at a timing tostart a processing per macroblock, for example.

The video ES buffer 1408A buffers the video stream generated by theencode/decode engine 1407 and supplies it to the multiplexing unit (MUX)1412. The video ES buffer 1408B buffers the video stream supplied fromthe demultiplexing unit (DMUX) 1413 and supplies it to the encode/decodeengine 1407.

The audio ES buffer 1409A buffers the audio stream generated by theaudio encoder 1410, and supplies it to the multiplexing unit (MUX) 1412.The audio ES buffer 1409B buffers the audio stream supplied from thedemultiplexing unit (DMUX) 1413 and supplies it to the audio decoder1411.

The audio encoder 1410 performs digital conversion on the audio signalinput from the connectivity 1321 (FIG. 38) or the like, and codes it ina predetermined system such as MPEG audio system or AudioCode number 3(AC3) system. The audio encoder 1410 sequentially writes the audiostream as coded audio signal into the audio ES buffer 1409A. The audiodecoder 1411 decodes the audio stream supplied from the audio ES buffer1409B, converts it into an analog signal, for example, and supplies theanalog signal as reproduced audio signal to the connectivity 1321 (FIG.38) or the like, for example.

The multiplexing unit (MUX) 1412 multiplexes the video stream and theaudio stream. The multiplexing method (or a format of the bit streamgenerated by the multiplexing) is optional. Further, at the time of themultiplexing, the multiplexing unit (MUX) 1412 can add predeterminedheader information or the like to the bit stream. That is, themultiplexing unit (MUX) 1412 can convert the format of the stream by themultiplexing. For example, the multiplexing unit (MUX) 1412 multiplexesthe video stream and the audio stream thereby to be converted into atransport stream as bit stream of transfer format. Further, for example,the multiplexing unit (MUX) 1412 multiplexes the video stream and theaudio stream thereby to be converted into data of recording file format(file data).

The demultiplexing unit (DMUX) 1413 demultiplexes the bit stream inwhich the video stream and the audio stream are multiplexed in a methodcorresponding to the multiplexing by the multiplexing unit (MUX) 1412.That is, the demultiplexing unit (DMUX) 1413 extracts the video streamand the audio stream from the bit stream read from the stream buffer1414 (separates into the video stream and the audio stream). That is,the demultiplexing unit (DMUX) 1413 can convert the format of the streamby the demultiplexing (inverse conversion to the conversion by themultiplexing unit (MUX) 1412). For example, the demultiplexing unit(DMUX) 1413 obtains and demultiplexes the transport stream supplied fromthe connectivity 1321 or the broadband modem 1333 (both in FIG. 38) viathe stream buffer 1414 thereby to be converted into the video stream andthe audio stream. Further, for example, the demultiplexing unit (DMUX)1413 can obtain and demultiplex the file data read from variousrecording mediums by the connectivity 1321 (FIG. 38) via the streambuffer 1414 thereby to be converted into the video stream and the audiostream.

The stream buffer 1414 buffers the bit stream. For example, the streambuffer 1414 buffers the transport stream supplied from the multiplexingunit (MUX) 1412, and supplies it to the connectivity 1321 or thebroadband modem 1333 (both in FIG. 38) at a predetermined timing or inresponse to an external request.

Further, for example, the stream buffer 1414 buffers the file datasupplied from the multiplexing unit (MUX) 1412, and supplies it to theconnectivity 1321 (FIG. 38) or the like at a predetermined timing or inresponse to an external request to be recoded in various recordingmediums.

Further, the stream buffer 1414 buffers the transport stream obtainedvia the connectivity 1321 or the broadband modem 1333 (both in FIG. 38),and supplies it to the demultiplexing unit (DMUX) 1413 at apredetermined timing or in response to an external request.

Further, the stream buffer 1414 buffers the file data read from variousrecording mediums in the connectivity 1321 (FIG. 38) or the like, andsupplies it to the demultiplexing unit (DMUX) 1413 at a predeterminedtiming or in response to an external request.

The operations of the thus-configured video processor 1332 will bedescribed below. For example, a video signal input from the connectivity1321 (FIG. 38) or the like into the video processor 1332 is convertedinto digital image data in a predetermined system such as 4:2:2Y/Cb/Crsystem by the video input processing unit 1401, and is sequentiallywritten into the frame memory 1405. The digital image data is read bythe first image enlargement/reduction unit 1402 or the second imageenlargement/reduction unit 1403, and is subjected to the formatconversion into a predetermined system such as 4:2:0Y/Cb/Cr system andthe enlargement/reduction processing to be written into the frame memory1405 again. The image data is coded by the encode/decode engine 1407 andwritten as video stream into the video ES buffer 1408A.

Further, an audio signal input from the connectivity 1321 (FIG. 38) orthe like into the video processor 1332 is coded by the audio encoder1410 and written as audio stream into the audio ES buffer 1409A.

The video stream in the video ES buffer 1408A and the audio stream inthe audio ES buffer 1409A are read and multiplexed by the multiplexingunit (MUX) 1412 to be converted into a transport stream or file data.The transport stream generated by the multiplexing unit (MUX) 1412 isbuffered by the stream buffer 1414 and then output to an externalnetwork via the connectivity 1321 or the broadband modem 1333 (both inFIG. 38). Further, the file data generated by the multiplexing unit(MUX) 1412 is buffered by the stream buffer 1414 and then output to theconnectivity 1321 (FIG. 38) or the like, for example, to be recorded invarious recording mediums.

Further, the transport stream input from the external network into thevideo processor 1332 via the connectivity 1321 or the broadband modem1333 (both in FIG. 38), for example, is buffered by the stream buffer1414 and then demultiplexed by the demultiplexing unit (DMUX) 1413.Further, the file data read from various recording mediums by theconnectivity 1321 (FIG. 38) or the like, for example, and input into thevideo processor 1332 is buffered by the stream buffer 1414 and thendemultiplexed by the demultiplexing (DMUX) 1413. That is, the transportstream or the file data input into the video processor 1332 is separatedinto the video stream and the audio stream by the demultiplexing unit(DMUX) 1413.

The audio stream is supplied to the audio decoder 1411 via the audio ESbuffer 1409B and decoded thereby to reproduce the audio signal. Thevideo stream is written into the video ES buffer 1408B, and is thensequentially read and decoded by the encode/decode engine 1407 to bewritten into the frame memory 1405. The decoded image data is subjectedto the enlargement/reduction processing by the second imageenlargement/reduction unit 1403 to be written into the frame memory1405. The decoded image data is then read by the video output processingunit 1404, is subjected to format conversion into a predetermined systemsuch as 4:2:2Y/Cb/Cr, and is further converted into an analog signalthereby to reproduce and output the video signal

When the present disclosure is applied to the thus-configured videoprocessor 1332, the present disclosure according to each exemplaryembodiment described above may be applied to the encode/decode engine1407. That is, for example, the encode/decode engine 1407 may have thefunctions of the coding device or the decoding device according to thefirst exemplary embodiment. By doing so, the video processor 1332 canobtain the similar effects to the above effects described with referenceto FIG. 1 to FIG. 20.

The present disclosure (or the functions of the image coding device orthe image decoding device according to each exemplary embodimentdescribed above) may be realized in hardware such as logic circuit, insoftware such as incorporated program, or in both of them in theencode/decode engine 1407.

(Other Exemplary Structure of Video Processor)

FIG. 40 illustrates other exemplary schematic structure of the videoprocessor 1332 (FIG. 38) to which the present disclosure is applied. Inthe example of FIG. 40, the video processor 1332 has the function ofcoding and decoding video data in a predetermined system.

More specifically, as illustrated in FIG. 40, the video processor 1332has a control unit 1511, a display interface 1512, a display engine1513, an image processing engine 1514, and an internal memory 1515. Thevideo processor 1332 further has a codec engine 1516, a memory interface1517, a multiplexing/demultiplexing unit (MUX DMUX) 1518, a networkinterface 1519, and a video interface 1520.

The control unit 1511 controls the operations of each processing unit inthe video processor 1332 such as the display interface 1512, the displayengine 1513, the image processing engine 1514, and the codec engine1516.

As illustrated in FIG. 40, the control unit 1511 has a main CPU 1531, asub-CPU 1532, and a system controller 1533. The main CPU 1531 executes aprogram or the like for controlling the operations of each processingunit in the video processor 1332. The main CPU 1531 generates a controlsignal according to the program or the like, and supplies it to eachprocessing unit (or controls the operations of each processing unit).The sub-CPU 1532 plays an auxiliary role for the main CPU 1531. Forexample, the sub-CPU 1532 executes a child process or sub-routine of theprogram or the like executed by the main CPU 1531. The system controller1533 controls the operations of the main CPU 1531 and the sub-CPU 1532,such as designating the programs to be executed by the main CPU 1531 andthe sub-CPU 1532.

The display interface 1512 outputs image data to the connectivity 1321(FIG. 38) or the like under control of the control unit 1511. Forexample, the display interface 1512 converts the digital image data intoan analog signal, and outputs it as reproduced video signal or as thedigital image data to a monitor device or the like of the connectivity1321 (FIG. 38).

The display engine 1513 performs various conversion processing such asformat conversion, size conversion, and color gamut conversion on theimage data under control of the control unit 1511 in order to match withthe hardware specification of the monitor device or the like fordisplaying the image.

The image processing engine 1514 performs a predetermined imageprocessing such as filter processing for improvement in image quality onthe image data under control of the control unit 1511.

The internal memory 1515 is a memory provided inside the video processor1332, which is shared among the display engine 1513, the imageprocessing engine 1514, and the codec engine 1516. The internal memory1515 is used for exchanging data among the display engine 1513, theimage processing engine 1514, and the codec engine 1516, for example.For example, the internal memory 1515 stores data supplied from thedisplay engine 1513, the image processing engine 1514, or the codecengine 1516, and supplies the data to the display engine 1513, the imageprocessing engine 1514, or the codec engine 1516 as needed (in responseto a request, for example). The internal memory 1515 may be realized byany storage device, and is desirably realized by a semiconductor memorywith a relatively smaller capacity (than the external memory 1312, forexample) and high response speed, such as static random access memory(SRAM), since it is generally used for storing a small capacity of datasuch as image data in units of block or parameters in many cases.

The codec engine 1516 performs a processing of coding or decoding theimage data. The coding/decoding system to which the codec engine 1516corresponds is optional, and one or more systems may be employed. Forexample, the codec engine 1516 may include the codec function in aplurality of coding/decoding systems, and may code image data or decodecoded data in a system selected from among them.

In the example illustrated in FIG. 40, the codec engine 1516 has thefunction blocks for codec processing, such as MPEG-2 Video 1541,AVC/H.264 1542, HEVC/H.265 1543, HEVC/H.265 (Scalable) 1544, HEVC/H.265(Multi-view) 1545, and MPEG-DASH 1551.

The MPEG-2 Video 1541 is a function block for coding or decoding imagedata in the MPEG-2 system. The AVC/H.264 1542 is a function block forcoding or decoding image data in the AVC system. The HEVC/H.265 1543 isa function block for coding or decoding image data in the HEVC system.The HEVC/H.265 (Scalable) 1544 is a function block for performingscalable coding or scalable decoding on image data in the HEVC system.The HEVC/H.265 (Multi-view) 1545 is a function block for performingmulti-view coding or multi-view decoding on image data in the HEVCsystem.

The MPEG-DASH 1551 is a function block for exchanging image data in theMPEG-Dynamic Adaptive Streaming over HTTP (MPEG-DASH) system. MPEG-DASHis a technique for streaming a video by use of HyperText TransferProtocol (HTTP), and is characterized by selecting and transmitting anappropriate item of coding data from among a plurality of items ofpreviously-prepared coding data having mutually different resolutions inunits of segment. The MPEG-DASH 1551 generates a stream conforming tothe standard or conducts transmission control on the stream, and usesthe MPEG-2 Video 1541 to the HEVC/H.265 (Multi-view) 1545 for coding ordecoding image data.

The memory interface 1517 is an interface for the external memory 1312.Data supplied from the image processing engine 1514 or the codec engine1516 is supplied to the external memory 1312 via the memory interface1517. Further, data read from the external memory 1312 is supplied tothe video processor 1332 (the image processing engine 1514 or the codecengine 1516) via the memory interface 1517.

The multiplexing/demultiplexing unit (MUX DMUX) 1518 multiplexes ordemultiplexes various items of data for images such as coding data bitstream, image data, and video signal. Any multiplexing/demultiplexingmethod is possible. For example, in multiplexing, themultiplexing/demultiplexing unit (MUX DMUX) 1518 can not only put aplurality of items of data into one item of data but also addpredetermined header information or the like to the data. Indemultiplexing, the multiplexing/demultiplexing unit (MUX DMUX) 1518 cannot only divide one item of data into a plurality of items of data butalso add predetermined header information or the like to each item ofdivided data. That is, the multiplexing/demultiplexing unit (MUX DMUX)1518 can convert a data format by multiplexing/demultiplexing. Forexample, the multiplexing/demultiplexing unit (MUX DMUX) 1518multiplexes bit streams to be converted into a transport stream as bitstream for transfer format, or data (file data) for recording fileformat. Of course, inverse conversion is also possible bydemultiplexing.

The network interface 1519 is an interface for the broadband modem 1333or the connectivity 1321 (both in FIG. 38), for example. The videointerface 1520 is an interface for the connectivity 1321 or the camera1322 (both in FIG. 38), for example.

The operations of the video processor 1332 will be described below byway of example. For example, when a transport stream is received from anexternal network via the connectivity 1321 or the broadband modem 1333(both in FIG. 38), the transport stream is supplied to themultiplexing/demultiplexing unit (MUX DMUX) 1518 via the networkinterface 1519 to be demultiplexed, and is decoded by the codec engine1516. The image data obtained by the coding of the codec engine 1516 issubjected to a predetermined image processing by the image processingengine 1514, for example, is subjected to predetermined conversion bythe display engine 1513, and is supplied to the connectivity 1321 (FIG.38) or the like via the display interface 1512 to display the image onthe monitor. Further, for example, the image data obtained by thedecoding of the codec engine 1516 is coded by the codec engine 1516again, is multiplexed and converted into file data by themultiplexing/demultiplexing unit (MUX DMUX) 1518, and is output to theconnectivity 1321 (FIG. 38) or the like via the video interface 1520 tobe recorded in various recording mediums.

Further, for example, the file data of the coding data as coded imagedata, which is read from a recording medium (not illustrated) by theconnectivity 1321 (FIG. 38) or the like, is supplied to themultiplexing/demultiplexing unit (MUX DMUX) 1518 via the video interface1520 to be demultiplexed, and is decoded by the codec engine 1516. Theimage data obtained by the decoding of the codec engine 1516 issubjected to a predetermined image processing by the image processingengine 1514, is subjected to predetermined conversion by the displayengine 1513, and is supplied to the connectivity 1321 (FIG. 38) or thelike via the display interface 1512 to display the image on the monitor.Further, for example, the image data obtained by the decoding of thecodec engine 1516 is coded by the codec engine 1516 again, ismultiplexed by the multiplexing/demultiplexing unit (MUX DMUX) 1518 tobe converted into a transport stream, and is supplied to theconnectivity 1321 or the broadband modem 1333 (both in FIG. 38) via thenetwork interface 1519 to be transmitted to other device (notillustrated).

Image data or other data is exchanged among the respective processingunits in the video processor 1332 by use of the internal memory 1515 orthe external memory 1312, for example. The power management module 1313controls power supplying to the control unit 1511, for example.

When the present disclosure is applied to the thus-configured videoprocessor 1332, the present disclosure according to each exemplaryembodiment described above may be applied to the codec engine 1516. Thatis, for example, the codec engine 1516 may have the function blocks forrealizing the coding device or the decoding device according to thefirst exemplary embodiment. Further, for example, by the codec engine1516 doing so, the video processor 1332 can obtain the similar effectsto the above effects described with reference to FIG. 1 to FIG. 20.

In the codec engine 1516, the present disclosure (or the functions ofthe image coding device or the image decoding device according to eachexemplary embodiment described above) may be realized in hardware suchas logic circuit, in software such as incorporated program, or in bothof them.

Two exemplary structures of the video processor 1332 have been describedabove, but the structure of the video processor 1332 is arbitrary, andmay be other than the two examples described above. Further, the videoprocessor 1332 may be configured in one semiconductor chip or may beconfigured in a plurality of semiconductor chips. For example, the videoprocessor 1332 may be assumed as a 3D laminated LSI in which a pluralityof semiconductors are laminated. Further, the video processor 1332 maybe realized in a plurality of LSIs.

(Exemplary Applications to Device)

The video set 1300 can be incorporated into various devices forprocessing image data. For example, the video set 1300 can beincorporated into the TV set 900 (FIG. 31), the cell phone 920 (FIG.32), the recording/reproducing device 940 (FIG. 33), the imaging device960 (FIG. 34), and the like. The video set 1300 is incorporated into adevice so that the device can obtain the similar effects to the aboveeffects described with reference to FIG. 1 to FIG. 20.

Further, the video set 1300 may be incorporated into the terminaldevices such as the personal computer 1004, the AV device 1005, thetablet device 1006, and the cell phone 1007 in the data transmissionsystem 1000 in FIG. 35, the broadcast station 1101 and the terminaldevice 1102 in the data transmission system 1100 in FIG. 36, and theimaging device 1201 and the scalable coding data storage device 1202 inthe imaging system 1200 in FIG. 37, for example. The video set 1300 isincorporated into a device so that the device can obtain the similareffects to the above effects described with reference to FIG. 1 to FIG.20.

Even part of each structure of the video set 1300 including the videoprocessor 1332 can be accomplished as a structure to which the presentdisclosure is applied. For example, only the video processor 1332 can beaccomplished as a video processor to which the present disclosure isapplied. For example, as described above, the processor indicated in thedotted line 1341 or the video module 1311 can be accomplished as aprocessor or module to which the present disclosure is applied.Furthermore, for example, the video module 1311, the external memory1312, the power management module 1313, and the frontend module 1314 canbe combined to be accomplished as a video unit 1361 to which the presentdisclosure is applied. Any structure can obtain the similar effects tothe above effects described with reference to FIG. 1 to FIG. 20.

That is, any structure including the video processor 1332 can beincorporated into various devices for processing image data similarly tothe video set 1300. For example, the video processor 1332, the processorindicated in the dotted line 1341, the video module 1311, or the videounit 1361 can be incorporated into the TV set 900 (FIG. 31), the cellphone 920 (FIG. 32), the recording/reproducing device 940 (FIG. 33), theimaging device 960 (FIG. 34), the terminal devices such as the personalcomputer 1004, the AV device 1005, the tablet device 1006, and the cellphone 1007 in the data transmission system 1000 in FIG. 35, thebroadcast station 1101 and the terminal device 1102 in the datatransmission system 1100 in FIG. 36, and the imaging device 1201 and thescalable coding data storage device 1202 in the imaging system 1200 inFIG. 37. Any structure to which the present disclosure is applied isincorporated into a device so that the device can obtain the similareffects to the above effects described with reference to FIG. 1 to FIG.20 similarly to the video set 1300.

There have been described the examples, in the present specification, inwhich various items of information such as deltaQP, ΔQP_(C), andChromaQPOffset are multiplexed on coding data to be transmitted from thecoding side to the decoding side. However, a method for transmitting theinformation is not limited to the examples. For example, the informationmay be transmitted or recorded as individual item of data associatedwith the coding data without being multiplexed on the coding data.Herein, “associating” indicates linking an image (which may be part ofan image such as slice or block) included in a bit stream withinformation corresponding to the image at the time of the decoding. Thatis, the information may be transmitted via a different transmission pathfrom the coding data. Further, the information may be recoded in adifferent recording medium from the coding data (or a differentrecording area in the same recoding medium). Furthermore, theinformation and the coding data may be associated in any unit such asframes, frame, or part of a frame.

In the present specification, the system indicates a set of components(such as devices and modules (parts)), and all the components do notneed to be present in the same casing. Therefore, a system may be aplurality of devices housed in different casings and connected via anetwork, and one device in which a plurality of modules are housed inone casing.

The effects described in the present specification are exemplary and notrestrictive, and other effects may be possible.

The exemplary embodiments in the present disclosure are not limited tothe above exemplary embodiments, and can be variously changed withoutdeparting from the spirit of the present disclosure.

For example, the present disclosure can be applied to a coding device ora decoding device in a coding system capable of performing transformskip other than the HEVC system.

Further, the present disclosure can be applied to a coding device or adecoding device used for receiving a coding stream via network mediumsuch as satellite broadcasting, cable TV, Internet or cell phone, orprocessing it in a storage medium such as optical disk, magnetic disk,or flash memory.

Furthermore, the present disclosure can employ a cloud computingstructure for distributing one function among a plurality of devices viaa network and performing cooperative processing.

Each step described in the above flowcharts can be performed in onedevice, or distributed and performed in a plurality of devices.

Further, when a plurality of series of processing are included in onestep, the series of processing included in one step can be performed inone device, or distributed or performed in a plurality of devise.

The preferred exemplary embodiments of the present disclosure have beendescribed above in detail with reference to the accompanying drawings,but the present disclosure is not limited to the examples. Variousmodifications or corrections can be made within the technical scopedescribed in Claims by those skilled in the art, and are assumed to beencompassed within the technical scope of the present disclosure.

The present technique may also take configurations as below.

(1) An image coding device including:

a chrominance signal quantization determination unit for determining achrominance signal quantization parameter with a higher quantizationaccuracy than a luminance signal quantization parameter in an image;

a quantization unit for quantizing the image by use of the luminancesignal quantization parameter and the chrominance signal quantizationparameter determined by the chrominance signal quantizationdetermination unit; and

a coding unit for coding the image quantized by the quantization unitthereby to generate a coding stream.

(2) The image coding device according to (1),

wherein the chrominance signal quantization determination unitdetermines the chrominance signal quantization parameter such that whenthe chrominance signal quantization parameter increases by 12, it isquantized twice as coarsely as the luminance signal quantizationparameter.

(3) The image coding device according to (1) or (2), further including:

a transmission unit for transmitting the coding stream generated by thecoding unit, a parameter deltaQP for the luminance signal, and aparameter ΔQP_(C) for the chrominance signal in a coding unit withpredefined magnitude.

(4) The image coding device according to (3),

wherein ΔQP_(C) is calculated in coding unit.

(5) The image coding device according to (3) or (4),

wherein the value of ΔQP_(C) is 0 or 1.

(6) The image coding device according to any of (3) to (5),

wherein a color space is YCbCr, and

the transmission unit transmits the independent values of ΔQP_(C) forthe Cb signal and the Cr signal.

(7) The image coding device according to any of (3) to (6),

wherein assuming a quantization parameter QP_(Y) for the luminancesignal, a quantization parameter QP_(C) for the chrominance signal, aquantization parameter offset offset for the chrominance signal, and adefined relational equation YtoC between the luminance signalquantization parameter and the chrominance signal quantizationparameter, QP_(C) is calculated as:

QP _(C)=2*YtoC(QP _(Y)+offset)+ΔQP _(C)  [Mathematical Formula 8]

(8) The image coding device according to any of (3) to (6),

wherein assuming a quantization parameter QP_(Y) for the luminancesignal, a quantization parameter QP_(C) for the chrominance signal, aquantization parameter offset offset for the chrominance signal, adefined relational equation YtoC between the luminance signalquantization parameter and the chrominance signal quantizationparameter, and an integer n of 2 or more, QP_(C) is calculated as:

QP _(C) =n*YtoC(QP _(Y)+offset)+ΔQP _(C)  [Mathematical Formula 9]

where the value of ΔQPC is 0, 1, 2 . . . , n−1.

(9) The image coding device according to any of (1) to (5), (7), and(8),

wherein a color space is YDzDx.

(10) The image coding device according to any of (1) to (9),

wherein the chrominance signal quantization determination unitdetermines a chrominance signal quantization parameter separately from aluminance signal quantization parameter in an image of an enhancementlayer with an input signal with wide color gamut when performing ascalability coding processing based on color gamut scalability.

(11) The image coding device according to (10),

wherein a chrominance signal quantization parameter offset transmittedtogether with a coding stream as coded image in the enhancement layertakes a negative value.

(12) The image coding device according to any of (1) to (11),

wherein when a predetermined flag is 0 in syntax transmitted togetherwith a coding stream as coded image, the chrominance signal quantizationparameter determined by the chrominance signal quantizationdetermination unit is transmitted together with a coded coding stream.

(13) An image coding method,

wherein an image coding device:

determines a chrominance signal quantization parameter with a higherquantization accuracy than a luminance signal quantization parameter inan image,

quantizes the image by use of the luminance signal quantizationparameter and the determined chrominance signal quantization parameter,and

codes the quantized image thereby to generate a coding stream.

(14) An image decoding device including:

a decoding unit for decoding a coding stream thereby to generate animage

a chrominance signal quantization determination unit for determining achrominance signal quantization parameter with a higher quantizationaccuracy than a luminance signal quantization parameter in the imagegenerated by the decoding unit; and

an inverse quantization unit for inversely quantizing the imagegenerated by the decoding unit by use of the luminance signalquantization parameter and the chrominance signal quantization parameterdetermined by the chrominance signal quantization determination unit.

(15) The image decoding device according to (14),

wherein the chrominance signal quantization determination unitdetermines the chrominance signal quantization parameter such that whenthe chrominance signal quantization parameter increases by 12, it isquantized twice as coarsely as the luminance signal quantizationparameter.

(16) The image decoding device according to (15), further including:

a reception unit for receiving the coding stream, a parameter deltaQPfor the luminance signal, and a parameter ΔQP_(C) for the chrominancesignal in coding unit with predefined magnitude.

(17) The image decoding device according to (16),

wherein ΔQP_(C) is calculated in coding unit.

(18) The image decoding device according to (16) or (17),

wherein the value of ΔQP_(C) is 0 or 1.

(19) The image decoding device according to any of (16) to (18),

wherein a color space is YCbCr, and

the reception unit receives the independent values of ΔQP_(C) for the Cbsignal and the Cr signal.

(20) An image decoding method,

wherein an image decoding device:

decodes a coding stream thereby to generate an image,

determines a chrominance signal quantization parameter with a higherquantization accuracy than a luminance signal quantization parameter inthe generated image, and

inversely quantizes the generated image by use of the luminance signalquantization parameter and the determined chrominance signalquantization parameter.

REFERENCE SIGNS LIST

-   10 Coding device-   12 Coding unit-   13 Transmission unit-   35 Quantization unit-   36 Coding unit-   38 Inverse quantization unit-   49 Rate control unit-   50 Chrominance signal quantization unit-   51 Chrominance signal inverse quantization unit-   110 Decoding device-   132 Lossless decoding unit-   133 Inverse quantization unit-   146 Chrominance signal inverse quantization unit

1. An image coding device comprising: a chrominance signal quantizationdetermination unit for determining a chrominance signal quantizationparameter with a higher quantization accuracy than a luminance signalquantization parameter in an image; a quantization unit for quantizingthe image by use of the luminance signal quantization parameter and thechrominance signal quantization parameter determined by the chrominancesignal quantization determination unit; and a coding unit for coding theimage quantized by the quantization unit thereby to generate a codingstream.
 2. The image coding device according to claim 1, wherein thechrominance signal quantization determination unit determines thechrominance signal quantization parameter such that when the chrominancesignal quantization parameter increases by 12, it is quantized twice ascoarsely as the luminance signal quantization parameter.
 3. The imagecoding device according to claim 2, further comprising: a transmissionunit for transmitting the coding stream generated by the coding unit, aparameter deltaQP for the luminance signal, and a parameter ΔQP_(C) forthe chrominance signal in a coding unit with predefined magnitude. 4.The image coding device according to claim 3, wherein ΔQP_(C) iscalculated in coding unit.
 5. The image coding device according to claim3, wherein the value of ΔQP_(C) is 0 or
 1. 6. The image coding deviceaccording to claim 3, wherein a color space is YCbCr, and thetransmission unit transmits the independent values of ΔQP_(C) for the Cbsignal and the Cr signal.
 7. The image coding device according to claim3, wherein assuming a quantization parameter QP_(Y) for the luminancesignal, a quantization parameter QP_(C) for the chrominance signal, aquantization parameter offset offset for the chrominance signal, and adefined relational equation YtoC between the luminance signalquantization parameter and the chrominance signal quantizationparameter, QP_(C) is calculated as:QP _(C)=2*YtoC(QP _(Y)+offset)+ΔQP _(C)  [Mathematical Formula 10] 8.The image coding device according to claim 3, wherein assuming aquantization parameter QP_(Y) for the luminance signal, a quantizationparameter QP_(C) for the chrominance signal, a quantization parameteroffset offset for the chrominance signal, a defined relational equationYtoC between the luminance signal quantization parameter and thechrominance signal quantization parameter, and an integer n of 2 ormore, QP_(C) is calculated as:QP _(C) =n*YtoC(QP _(Y)+offset)+ΔQP _(C)  [Mathematical Formula 11]where the value of ΔQPC is 0, 1, 2 . . . , n−1.
 9. The image codingdevice according to claim 1, wherein a color space is YDzDx.
 10. Theimage coding device according to claim 1, wherein the chrominance signalquantization determination unit determines a chrominance signalquantization parameter separately from a luminance signal quantizationparameter in an image of an enhancement layer with an input signal withwide color gamut when performing a scalability coding processing basedon color gamut scalability.
 11. The image coding device according toclaim 10, wherein a chrominance signal quantization parameter offsettransmitted together with a coding stream as coded image in theenhancement layer takes a negative value.
 12. The image coding deviceaccording to claim 1, wherein when a predetermined flag is 0 in syntaxtransmitted together with a coding stream as coded image, thechrominance signal quantization parameter determined by the chrominancesignal quantization determination unit is transmitted together with acoded coding stream.
 13. An image coding method, wherein an image codingdevice: determines a chrominance signal quantization parameter with ahigher quantization accuracy than a luminance signal quantizationparameter in an image, quantizes the image by use of the luminancesignal quantization parameter and the determined chrominance signalquantization parameter, and codes the quantized image thereby togenerate a coding stream.
 14. An image decoding device comprising: adecoding unit for decoding a coding stream thereby to generate an imagea chrominance signal quantization determination unit for determining achrominance signal quantization parameter with a higher quantizationaccuracy than a luminance signal quantization parameter in the imagegenerated by the decoding unit; and an inverse quantization unit forinversely quantizing the image generated by the decoding unit by use ofthe luminance signal quantization parameter and the chrominance signalquantization parameter determined by the chrominance signal quantizationdetermination unit.
 15. The image decoding device according to claim 14,wherein the chrominance signal quantization determination unitdetermines the chrominance signal quantization parameter such that whenthe chrominance signal quantization parameter increases by 12, it isquantized twice as coarsely as the luminance signal quantizationparameter.
 16. The image decoding device according to claim 15, furthercomprising: a reception unit for receiving the coding stream, aparameter deltaQP for the luminance signal, and a parameter ΔQP_(C) forthe chrominance signal in coding unit with predefined magnitude.
 17. Theimage decoding device according to claim 16, wherein ΔQP_(C) iscalculated in coding unit.
 18. The image decoding device according toclaim 16, wherein the value of ΔQP_(C) is 0 or
 1. 19. The image decodingdevice according to claim 16, wherein a color space is YCbCr, and thereception unit receives the independent values of ΔQP_(C) for the Cbsignal and the Cr signal.
 20. An image decoding method, wherein an imagedecoding device: decodes a coding stream thereby to generate an image,determines a chrominance signal quantization parameter with a higherquantization accuracy than a luminance signal quantization parameter inthe generated image, and inversely quantizes the generated image by useof the luminance signal quantization parameter and the determinedchrominance signal quantization parameter.